U.S. patent application number 17/605059 was filed with the patent office on 2022-05-12 for method for producing light-emitting particles, light-emitting particles, light-emitting particle dispersion, ink composition, and light-emitting element.
This patent application is currently assigned to DIC Corporation. The applicant listed for this patent is DIC Corporation. Invention is credited to Yoshio Aoki, Koichi Endo, Takuo Hayashi, Shinichi Hirata, Misao Horigome, Masahiro Horiguchi, Yasuo Umezu, Jianjun Yuan.
Application Number | 20220145108 17/605059 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-12 |
United States Patent
Application |
20220145108 |
Kind Code |
A1 |
Endo; Koichi ; et
al. |
May 12, 2022 |
METHOD FOR PRODUCING LIGHT-EMITTING PARTICLES, LIGHT-EMITTING
PARTICLES, LIGHT-EMITTING PARTICLE DISPERSION, INK COMPOSITION, AND
LIGHT-EMITTING ELEMENT
Abstract
Provided are light-emitting particles having high stability
while having perovskite-type semiconductor nanocrystals having
excellent light-emitting properties, a method for producing the
same, and a light-emitting particle dispersion, an ink composition,
and a light-emitting element containing such light-emitting
particles. The method for producing light-emitting particles of the
present invention includes a step of preparing parent particles 91
composed of perovskite-type semiconductor nanocrystals 911 having
light-emitting properties and a surface layer 912 which is composed
of ligands coordinated on the surface of the semiconductor
nanocrystal 911 and in which the ligand molecules form a siloxane
bond with each other, and a step of forming a polymer layer 93 by
coating the surface of the parent particle 91 with a hydrophobic
polymer.
Inventors: |
Endo; Koichi;
(Kitaadachi-gun, JP) ; Umezu; Yasuo;
(Kitaadachi-gun, JP) ; Aoki; Yoshio;
(Kitaadachi-gun, JP) ; Hirata; Shinichi;
(Kitaadachi-gun, JP) ; Hayashi; Takuo;
(Kitaadachi-gun, JP) ; Horiguchi; Masahiro;
(Kitaadachi-gun, JP) ; Horigome; Misao;
(Kitaadachi-gun, JP) ; Yuan; Jianjun;
(Kitaadachi-gun, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIC Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
DIC Corporation
Tokyo
JP
|
Appl. No.: |
17/605059 |
Filed: |
May 13, 2020 |
PCT Filed: |
May 13, 2020 |
PCT NO: |
PCT/JP2020/019142 |
371 Date: |
October 20, 2021 |
International
Class: |
C09D 11/322 20060101
C09D011/322; H05B 33/14 20060101 H05B033/14; C08F 2/50 20060101
C08F002/50; C09K 11/06 20060101 C09K011/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 21, 2019 |
JP |
2019-095110 |
Claims
1. A method for producing light-emitting particles comprising: step
1 of mixing a solution containing a raw material compound for
semiconductor nanocrystals and a solution containing a compound
containing Si and having a reactive group capable of forming a
siloxane bond to precipitate perovskite-type semiconductor
nanocrystals having light emitting properties and coordinate the
compound on the surfaces of semiconductor nanocrystal, and then
condensing the reactive group in the coordinated compound to obtain
parent particles each having a surface layer having the siloxane
bond formed on the surface of the semiconductor nanocrystal, and
step 2 of then forming a polymer layer by coating the surface of
each parent particle with a hydrophobic polymer.
2. The method for producing light-emitting particles according to
claim 1, wherein the average particle size of the semiconductor
nanocrystals is 40 nm or less.
3. The method for producing light-emitting particles according to
claim 1, wherein the surface layer has a thickness of 0.5 to 50
nm.
4. The method for producing light-emitting particles according to
claim 1, wherein the compound having a reactive group has a binding
group that binds to a cation contained in the semiconductor
nanocrystal.
5. The method for producing light-emitting particles according to
claim 4, wherein the binding group is at least one of a carboxyl
group, a mercapto group, and an amino group.
6. The method for producing light-emitting particles according to
claim 1, wherein the polymer layer has a thickness of 0.5 to 100
nm.
7. The method for producing light-emitting particles according to
claim 1, wherein the hydrophobic polymer is obtained by carrying at
least one polymerizable unsaturated monomer that is soluble in a
non-aqueous solvent and becomes insoluble or sparingly soluble
after polymerization, together with a polymer having a
polymerizable unsaturated group soluble in a non-aqueous solvent on
the surface of the parent particle and then polymerizing the
polymer and the polymerizable unsaturated monomer.
8. The method for producing light-emitting particles according to
claim 7, wherein the non-aqueous solvent contains at least one of
an aliphatic hydrocarbon solvent and an alicyclic hydrocarbon
solvent.
9. Light-emitting particles each comprising: a parent particle
composed of a perovskite-type semiconductor nanocrystal having
light-emitting properties, and a surface layer which is composed of
ligands coordinated on the surface of the semiconductor nanocrystal
and in which ligand molecules form a siloxane bond, and a polymer
layer which covers the surface of the parent particle and is
composed of a hydrophobic polymer.
10. The light-emitting particles according to claim 9, wherein the
hydrophobic polymer is a polymer having a polymerizable unsaturated
group soluble in a non-aqueous solvent and at least one
polymerizable unsaturated monomer that is soluble in a non-aqueous
solvent and becomes insoluble or sparingly soluble after
polymerization.
11. A light-emitting particle dispersion comprising the
light-emitting particles according to claim 9 and a dispersion
medium for dispersing the light-emitting particles.
12. An ink composition comprising the light-emitting particles
according to claim 9, a photopolymerizable compound, and a
photopolymerization initiator.
13. The ink composition according to claim 12, wherein the
photopolymerizable compound is a photoradical polymerizable
compound.
14. The ink composition according to claim 12, wherein the
photopolymerization initiator is at least one selected from the
group consisting of alkylphenone compounds, acylphosphine oxide
compounds, and oxime ester compounds.
15. A light-emitting element having a light-emitting layer
containing the light-emitting particles according to claim 9.
16. The light-emitting element according to claim 15, further
comprising a light source unit that irradiates the light-emitting
layer with light.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing
light-emitting particles, light-emitting particles, a
light-emitting particle dispersion, an ink composition, and a
light-emitting element.
BACKGROUND ART
[0002] International standard BT.2020 (Broadcasting service 2020)
required for next-generation display elements is an extremely
ambitious standard, and it is difficult to meet it even with
current color filters and organic EL using pigments.
[0003] On the other hand, semiconductor nanocrystals with
light-emitting properties are materials that emit fluorescence or
phosphorescence with a narrow half-value width of emission
wavelength and are attracting attention as a material that can
satisfy BT.2020. Initially, CdSe and the like were used as
semiconductor nanocrystals, but recently, InP and the like have
been used in order to avoid harmfulness thereof.
[0004] However, the stability of InP is low and vigorous efforts
are being made with the aim of improving the stability. In
addition, since the emission wavelength of semiconductor
nanocrystals such as InP is determined by the particle size, it is
necessary to precisely control the dispersion of the particle size
in order to obtain light emission with a narrow half-value width
and there are many problems in the production thereof.
[0005] In recent years, semiconductor nanocrystals having a
perovskite-type crystal structure have been discovered and are
attracting attention (see, for example, PTL 1). A common
perovskite-type semiconductor nanocrystal is a compound represented
by CsPbX.sub.3 (X represents Cl, Br or I). In addition to the
particle size, perovskite-type semiconductor nanocrystals can
control the emission wavelength by adjusting the abundance ratio of
halogen atoms. Since this adjustment operation can be easily
performed, the perovskite-type semiconductor nanocrystal is
characterized in that the emission wavelength is more easily
controlled and therefore the productivity is higher than that of
the semiconductor nanocrystal such as InP.
[0006] As described above, the perovskite-type semiconductor
nanocrystal has extremely excellent light-emitting properties but
has a problem that it is easily destabilized by oxygen, moisture,
heat, and the like. Therefore, it is necessary to improve the
stability of perovskite-type semiconductor nanocrystals by some
method.
CITATION LIST
Patent Literature
[0007] PTL 1: JP-A-2017-222851
SUMMARY OF INVENTION
Technical Problem
[0008] An object of the present invention is to provide
light-emitting particles having high stability while having
perovskite-type semiconductor nanocrystals having excellent
light-emitting properties, a method for producing the same, and a
light-emitting particle dispersion, an ink composition, and a
light-emitting element containing such light-emitting
particles.
Solution to Problem
[0009] Such an object is achieved by the following inventions (1)
to (16).
[0010] (1) A method for producing light-emitting particles
including:
[0011] step 1 of mixing a solution containing a raw material
compound for semiconductor nanocrystals and a solution containing a
compound containing Si and having a reactive group capable of
forming a siloxane bond to precipitate perovskite-type
semiconductor nanocrystals having light emitting properties and
coordinate the compound on the surfaces of semiconductor
nanocrystal, and then condensing the reactive group in the
coordinated compound to obtain parent particles each having a
surface layer having the siloxane bond formed on the surface of the
semiconductor nanocrystal, and
[0012] step 2 of then forming a polymer layer by coating the
surface of each parent particle with a hydrophobic polymer.
[0013] (2) The method for producing light-emitting particles
according to (1) above, where the average particle size of the
semiconductor nanocrystals is 40 nm or less.
[0014] (3) The method for producing light-emitting particles
according to (1) or (2) above, where the surface layer has a
thickness of 0.5 to 50 nm.
[0015] (4) The method for producing light-emitting particles
according to any one of (1) to (3) above, where the compound having
a reactive group has a binding group that binds to a cation
contained in the semiconductor nanocrystal.
[0016] (5) The method for producing light-emitting particles
according to (4) above, where the binding group is at least one of
a carboxyl group, a mercapto group, and an amino group.
[0017] (6) The method for producing light-emitting particles
according to any one of (1) to (5) above, where the polymer layer
has a thickness of 5 to 100 nm.
[0018] (7) The method for producing light-emitting particles
according to any one of (1) to (6) above, where the hydrophobic
polymer is obtained by carrying at least one polymerizable
unsaturated monomer that is soluble in a non-aqueous solvent and
becomes insoluble or sparingly soluble after polymerization,
together with a polymer having a polymerizable unsaturated group
soluble in a non-aqueous solvent on the surface of the parent
particle and then polymerizing the polymer and the polymerizable
unsaturated monomer.
[0019] (8) The method for producing light-emitting particles
according to (7) above, where the non-aqueous solvent contains at
least one of an aliphatic hydrocarbon solvent and an alicyclic
hydrocarbon solvent.
[0020] (9) Light-emitting particles each including
[0021] a parent particle composed of a perovskite-type
semiconductor nanocrystal having light-emitting properties, and a
surface layer which is composed of ligands coordinated on the
surface of the semiconductor nanocrystal and in which ligand
molecules form a siloxane bond, and
[0022] a polymer layer which covers the surface of the parent
particle and is composed of a hydrophobic polymer.
[0023] (10) The light-emitting particles according to (9) above,
where the hydrophobic polymer is a polymer having a polymerizable
unsaturated group soluble in a non-aqueous solvent and at least one
polymerizable unsaturated monomer that is soluble in a non-aqueous
solvent and becomes insoluble or sparingly soluble after
polymerization.
[0024] (11) A light-emitting particle dispersion comprising the
light-emitting particles according to (9) or (10) above and a
dispersion medium for dispersing the light-emitting particles.
[0025] (12) An ink composition comprising the light-emitting
particles according to (9) or (10) above, a photopolymerizable
compound, and a photopolymerization initiator.
[0026] (13) The ink composition according to (12) above, where the
photopolymerizable compound is a photoradical polymerizable
compound.
[0027] (14) The ink composition according to (12) or (13) above,
where the photopolymerization initiator is at least one selected
from the group consisting of alkylphenone compounds, acylphosphine
oxide compounds, and oxime ester compounds.
[0028] (15) A light-emitting element comprising a light-emitting
layer containing the light-emitting particles according to (9) or
(10) above.
[0029] (16) The light-emitting element according to (15) above,
further including a light source unit that irradiates the
light-emitting layer with light.
Advantageous Effects of Invention
[0030] According to the present invention, light-emitting particles
having excellent light-emitting properties and high stability due
to the presence of a surface layer and a polymer layer can be
obtained.
BRIEF DESCRIPTION OF DRAWINGS
[0031] FIG. 1 is a cross-sectional view showing an embodiment of a
light-emitting particle of the present invention.
[0032] FIG. 2 is a cross-sectional view showing an embodiment of
the light-emitting element of the present invention.
[0033] FIG. 3 is a schematic diagram showing a configuration of an
active matrix circuit.
[0034] FIG. 4 is a schematic diagram showing a configuration of an
active matrix circuit.
DESCRIPTION OF EMBODIMENTS
[0035] Hereinafter, the method for producing light-emitting
particles, the light-emitting particles, the light-emitting
particle dispersion, the ink composition, and the light-emitting
element of the present invention will be described in detail based
on the preferable embodiments shown in the accompanying
drawings.
[0036] FIG. 1 is a cross-sectional view showing an embodiment of a
light-emitting particle of the present invention.
[0037] <Light-Emitting Particles and Method for Producing the
Same>
[0038] A light-emitting particle 90 shown in FIG. 1 includes a
parent particle 91 having a perovskite-type semiconductor
nanocrystal having light-emitting properties (hereinafter, may be
simply referred to as "nanocrystal 911") and a surface layer 912
which is composed of ligands coordinated on the surface of the
nanocrystal 911 and in which the ligand molecules form a siloxane
bond, and a polymer layer 92 covering the surface of the parent
particle 91 and composed of a hydrophobic polymer. Therefore, since
the nanocrystals 911 are protected by the surface layer 912 and the
polymer layer 92, the light-emitting particles 90 can exhibit high
stability against oxygen, water, heat, and the like while
maintaining excellent light-emitting properties.
[0039] Such light-emitting particles 90 can be produced by a method
(method for producing a light-emitting element of the present
invention) including step 1 of mixing a solution containing a raw
material compound for semiconductor nanocrystals and a solution
containing a compound containing Si and having a reactive group
capable of forming a siloxane bond to precipitate perovskite-type
semiconductor nanocrystals having light-emitting properties and
coordinate the compound on the surfaces of the semiconductor
nanocrystals, and then condensing the reactive group in the
coordinated compound to obtain parent particles having a surface
layer having the siloxane bond formed on the surface of the
semiconductor nanocrystal, and step 2 of then forming a polymer
layer by coating the surface of each parent particle with a
hydrophobic polymer.
[0040] <<Step 1 (Parent Particle Preparation
Step)>>
[0041] First, to describe step 1 in detail, the light-emitting
particles 91 obtained through step 1 are the parent particles in
the next step, step 2, and each have the nanocrystal 911 and the
surface layer 912 covering the nanocrystal 911. The parent particle
91 per se can be used alone as a light-emitting particle.
[0042] [Nanocrystal 911]
[0043] The nanocrystal 911 obtained through step 1 is a nano-sized
crystal (nanocrystal particle) that has a perovskite-type crystal
structure and absorbs excitation light to emit fluorescence or
phosphorescence. The nanocrystal 911 is, for example, a crystal
having a maximum particle size of 100 nm or less as measured by a
transmission electron microscope or a scanning electron
microscope.
[0044] The nanocrystal 911 can be excited by, for example, light
energy or electrical energy of a predetermined wavelength and emit
fluorescence or phosphorescence.
[0045] The nanocrystal 911 having a perovskite-type crystal
structure is a compound represented by the general formula:
A.sub.aM.sub.bX.sub.c.
[0046] In the formula, A is at least one among organic cations and
metal cations. Examples of the organic cation include ammonium,
formamidinium, guanidinium, imidazolium, pyridinium, pyrrolidinium,
protonated thiourea, and the like, and examples of the metal cation
include cations of Cs, Rb, K, Na, Li, and the like.
[0047] M is at least one of metal cations. Examples of the metal
cation include cations of Ag, Au, Bi, Ca, Ce, Co, Cr, Cu, Eu, Fe,
Ga, Ge, Hf, In, Ir, Mg, Mn, Mo, Na, Nb, Nd, Ni, Os, Pb, Pd, Pt, Re,
Rh, Ru, Sb, Sm, Sn, Sr, Te, Ti, V, W, Zn, Zr, and the like.
[0048] X is at least one of anions. Examples of the anion include
chloride ion, bromide ion, iodide ion, cyanide ion, and the
like.
[0049] a is 1 to 4, b is 1 to 2, and c is 3 to 9.
[0050] The emission wavelength (emission color) of such a
nanocrystal 911 can be controlled by adjusting the particle size,
the type and abundance ratio of the anions constituting the X
site.
[0051] As a specific composition of the nanocrystal 911, the
nanocrystal 911 using Pb as M, such as CsPbBr.sub.3,
CH.sub.3NH.sub.3PbBr.sub.3, and CHN.sub.2H.sub.4PbBr.sub.3 is
preferable due to the excellent light intensity and quantum
efficiency. Further, the nanocrystal 911 using a metal cation other
than Pb as M such as CsPbBr.sub.3, CH.sub.3NH.sub.3PbBr.sub.3, and
CHN.sub.2H.sub.4PbBr.sub.3 is preferable due to the low toxicity
and a little impact on the environment.
[0052] The nanocrystal 911 may be a red light-emitting crystal that
emits light having an emission peak in the wavelength range of 605
to 665 nm (red light), may be a green light-emitting crystal that
emits light having an emission peak in the wavelength range of 500
to 560 nm (green light), and may be a blue light-emitting crystal
that emits light having an emission peak in the wavelength range of
420 to 480 nm (blue light). Further, in one embodiment, a
combination of these nanocrystals may be used.
[0053] Note that the wavelength of the emission peak of the
nanocrystal 911 can be determined, for example, in the fluorescence
spectrum or the phosphorescence spectrum measured by using an
absolute PL quantum yield measuring device.
[0054] The red light-emitting nanocrystals 911 preferably have an
emission peak in the wavelength range of 665 nm or less, 663 nm or
less, 660 nm or less, 658 nm or less, 655 nm or less, 653 nm or
less, 651 nm or less, 650 nm or less, 647 nm or less, 645 nm or
less, 643 nm or less, 640 nm or less, 637 nm or less, 635 nm or
less, 632 nm or less, or 630 nm or less, and preferably have an
emission peak in the wavelength range of 628 nm or more, 625 nm or
more, 623 nm or more, 620 nm or more, 615 nm or more, 610 nm or
more, 607 nm or more, or 605 nm or more.
[0055] These upper limit value and lower limit value can be
arbitrarily combined. Note that in the similar description below,
the upper limit value and the lower limit value described
individually can be arbitrarily combined.
[0056] The green light-emitting nanocrystals 911 preferably have an
emission peak in the wavelength range of 560 nm or less, 557 nm or
less, 555 nm or less, 550 nm or less, 547 nm or less, 545 nm or
less, 543 nm or less, 540 nm or less, 537 nm or less, 535 nm or
less, 532 nm or less, or 530 nm or less, and preferably have an
emission peak in the wavelength range of 528 nm or more, 525 nm or
more, 523 nm or more, 520 nm or more, 515 nm or more, 510 nm or
more, 507 nm or more, 505 nm or more, 503 nm or more, or 500 nm or
more.
[0057] The blue light-emitting nanocrystals 911 preferably have an
emission peak in the wavelength range of 480 nm or less, 477 nm or
less, 475 nm or less, 470 nm or less, 467 nm or less, 465 nm or
less, 463 nm or less, 460 nm or less, 457 nm or less, 455 nm or
less, 452 nm or less, or 450 nm or less, and preferably have an
emission peak in the wavelength range of 450 nm or more, 445 nm or
more, 440 nm or more, 435 nm or more, 430 nm or more, 428 nm or
more, 425 nm or more, 422 nm or more, or 420 nm or more.
[0058] The shape of the nanocrystal 911 is not particularly limited
and may be any geometric shape or any irregular shape. Examples of
the shape of the nanocrystal 911 include a rectangular
parallelepiped shape, a cube shape, a spherical shape, a regular
tetrahedron shape, an ellipsoidal shape, a pyramid shape, a disc
shape, a branch shape, a net shape, and a rod shape. Note that the
shape of the nanocrystal 911 is preferably a shape having little
directionality (for example, a spherical shape, a regular
tetrahedron shape, and the like). By using the nanocrystals 911
having such a shape, the light-emitting particles 90 reflecting the
shape can be obtained, and uniform dispersibility and fluidity when
an ink composition containing the light-emitting particles 90 is
prepared can be further enhanced.
[0059] The average particle size (volume average diameter) of the
nanocrystals 911 is preferably 40 nm or less, more preferably 30 nm
or less, and even more preferably 20 nm or less. Note that the
average particle size of the nanocrystals 911 is preferably 1 nm or
more, more preferably 1.5 nm or more, and even more preferably 2 nm
or more. The nanocrystals 911 having such an average particle size
are preferable since they easily emit light having a desired
wavelength.
[0060] Note that the average particle size of the nanocrystals 911
is obtained by measuring with a transmission electron microscope or
a scanning electron microscope and calculating the volume average
diameter.
[0061] By the way, the nanocrystals 911 have surface atoms that can
serve as coordination sites, and thus have high reactivity. The
nanocrystals 911 have such high reactivity and have a large surface
area as compared with general pigments, which facilitates
aggregation in the ink composition.
[0062] The nanocrystals 911 emit light due to the quantum size
effect. Therefore, when the nanocrystals 911 aggregate, a quenching
phenomenon occurs, which causes a decrease in the fluorescence
quantum yield and a decrease in brightness and color
reproducibility. In the present invention, since the nanocrystal
911 is coated with the surface layer 912 and the polymer layer 92,
the light-emitting particles 90 are less likely to aggregate even
when the ink composition was prepared, and the deterioration of
light-emitting properties due to the aggregation are less likely to
occur.
[0063] [Surface Layer 912]
[0064] The surface layer 912 obtained through step 1 is composed of
ligands capable of coordinating with the surface of the nanocrystal
911 and capable of forming a siloxane bond between the
molecules.
[0065] Such a ligand is a compound containing Si and having a
reactive group forming a siloxane bond. Preferably, this compound
further has a binding group that binds to a cation contained in the
nanocrystal 911.
[0066] As the reactive group, a hydrolyzable silyl group such as a
silanol group or an alkoxysilyl group having 1 to 6 carbon atoms is
preferable in that a siloxane bond is easily formed.
[0067] Examples of the binding group include a carboxyl group, an
amino group, an ammonium group, a mercapto group, a phosphine
group, a phosphine oxide group, a phosphoric acid group, a
phosphonic acid group, a phosphinic acid group, a sulfonic acid
group, a boronic acid group, and the like. Among them, the binding
group is preferably at least one of a carboxyl group, a mercapto
group, and an amino group. These binding groups have a higher
affinity for the cations contained in the nanocrystal 911 than the
reactive group described above. Therefore, the ligand can
coordinate with the binding group on the nanocrystal 911 side, and
can more easily and surely form the surface layer 912.
[0068] As such a ligand, one or more types of silicon compounds
containing a binding group can be contained, or two or more types
can be used in a combination.
[0069] Preferably, any one of a carboxyl group-containing silicon
compound, an amino group-containing silicon compound, and a
mercapto group-containing silicon compound can be contained, or two
or more of them can be used in a combination.
[0070] Specific examples of the carboxyl group-containing silicon
compound include, for example, 3-(trimethoxysilyl) propionic acid,
3-(triethoxysilyl) propionic acid, 2-,
carboxyethylphenylbis(2-methoxyethoxy)silane,
N-[3-(trimethoxysilyl)propyl]-N'-carboxymethylethylenediamine,
N-[3-(trimethoxysilyl)propyl]phthalamide,
N-[3-(trimethoxysilyl)propyl] ethylenediamine-N,N',N'-triacetic
acid, and the like.
[0071] On the other hand, specific examples of the amino
group-containing silicon compound include, for example,
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,
N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,
N-(2-aminoethyl)-3-aminopropylmethylethoxysilane,
N-(2-aminoethyl)-3-aminopropylmethyldipropoxysilane,
N-(2-aminoethyl)-3-aminopropylmethyldiisopropoxysilane,
N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,
N-(2-aminoethyl)-3-aminopropyltriethoxysilane,
N-(2-aminoethyl)-3-aminopropyltripropoxysilane,
N-(2-aminoethyl)-3-aminopropyltriisopropoxysilane,
N-(2-aminoethyl)-3-aminoisobutyldimethylmethoxysilane,
N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane,
N-(2-aminoethyl)-11-aminoundecyltrimethoxysilane,
N-(2-aminoethyl)-3-aminopropylsilanetriol,
3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine,
N-phenyl-3-aminopropyltrimethoxysilane,
N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine,
(aminoethylaminoethyl)phenyltrimethoxysilane,
(aminoethylaminoethyl)phenyltriethoxysilane,
(aminoethylaminoethyl)phenyltripropoxysilane,
(aminoethylaminoethyl)phenyltriisopropoxysilane,
(aminoethylaminomethyl)phenyltrimethoxysilane,
(aminoethylaminomethyl)phenyltriethoxysilane,
(aminoethylaminomethyl)phenyltripropoxysilane,
(aminoethylaminomethyl)phenyltriisopropoxysilane,
N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane,
N-(vinylbenzyl)-2-aminoethyl-3-aminopropylmethyldimethoxysilane,
N-.beta.-(N-vinylbenzylaminoethyl)-N-.gamma.-(N-vinylbenzyl)-.gamma.-amin-
opropyltrimethoxysilane,
N-.beta.-(N-di(vinylbenzyl)aminoethyl)-.gamma.-aminopropyltrimethoxysilan-
e,
N-.beta.-(N-di(vinylbenzyl)aminoethyl)-N-.gamma.-(N-vinylbenzyl)-.gamma-
.-aminopropyltrimethoxysilane,
methylbenzylaminoethylaminopropyltrimethoxysilane,
dimethylbenzylaminoethylaminopropyltrimethoxysilane,
benzylaminoethylaminopropyltrimethoxysilane,
benzylaminoethylaminopropyltriethoxysilane,
3-ureidopropyltriethoxysilane,
3-(N-phenyl)aminopropyltrimethoxysilane,
N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine,
(aminoethylaminoethyl)phenethyltrimethoxysilane,
(aminoethylaminoethyl)phenethyltriethoxysilane,
(aminoethylaminnoethyl)phenethyltripropoxysilane,
(aminoethylaminoethyl)phenethyltriisopropoxysilane,
(aminoethylaminomethyl)phenethyltrimethoxysilane,
(aminoethylaminomethyl)phenethyltriethoxysilane,
(aminoethylaminomethyl)phenethyltripropoxysilane,
(aminoethylaminomethyl)phenethyltriisopropoxysilane,
N-[2-[3-(triemethoxysilyl)propylamino]ethyl]ethylenediamine,
N-[2-[3-(triethoxysilyl)propylamino]ethyl]ethylenediamine,
N-[2-[3-(tripropoxysilyl)propylamino]ethyl]ethylenediamine,
N-[2-[3-(triisopropoxysilyl)propylamino]ethyl]ethylenediamine, and
the like.
[0072] Specific examples of the mercapto group-containing silicon
compound include, for example, 3-mercaptopropyltrimethoxysilane,
3-mercaptopropyltriethoxysilane,
3-mercaptopropylmethyldimethoxysilane,
3-mercaptopropylmethyldiethoxysilane,
2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane,
2-mercaptoethylmethyldimethoxysilane,
2-mercaptoethylmethyldiethoxysilane,
3-[ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanthiol,
and the like.
[0073] FIG. 1 shows an example of the parent particle 91. The
parent particle 91 shown in FIG. 1 has the surface layer 912 formed
by coordinating 3-aminopropyltrimethoxysilane as a ligand on the
surface of the nanocrystal 911 containing a Pb cation as an M
site.
[0074] The thickness of the surface layer 912 is preferably 0.5 to
50 nm, and more preferably 1.0 to 30 nm. If the light-emitting
particles 90 (parent particles 91) have the surface layer 912
having such a thickness, the stability of the nanocrystals 911 with
respect to heat can be sufficiently enhanced.
[0075] Note that the thickness of the surface layer 912 can be
changed by adjusting the number of atoms (chain length) of the
linking structure that connects the binding group and the reactive
group of the ligand.
[0076] Such a parent particle 91 can be easily prepared by mixing a
solution containing the raw material compound of the nanocrystal
911 and a solution containing a compound containing Si and having a
reactive group capable of forming a siloxane bond, and then
condensing the reactive group coordinated on the surface of the
precipitated nanocrystal 911. At this time, there are a production
method with heating and a production method without heating.
[0077] First, a method of producing the parent particles 91 by
heating will be described. Two solutions respectively containing a
raw material compound for synthesizing semiconductor nanocrystals
by a reaction are prepared, respectively. At this time, a compound
containing Si and having a reactive group capable of forming a
siloxane bond is added to either of the two solutions. Then, these
are mixed under an inert gas atmosphere and reacted under
temperature conditions of 140 to 260.degree. C. Then, a method of
precipitating nanocrystals by cooling to -20 to 30.degree. C. and
stirring can be mentioned. The precipitated nanocrystals 911 have
the surface layer 912 having a siloxane bond formed on the surface
thereof, and the nanocrystals can be obtained by a conventional
method such as centrifugation.
[0078] Specifically, for example, a solution containing cesium
carbonate, oleic acid, and an organic solvent is prepared. As the
organic solvent, 1-octadecene, dioctyl ether, diphenyl ether, and
the like can be used. At this time, it is preferable to adjust the
addition amount of cesium carbonate having 0.2 to 2 g and the
addition amount of oleic acid having 0.1 to 10 mL with respect to
40 mL of the organic solvent. The obtained solution is dried under
reduced pressure at 90 to 150.degree. C. for 10 to 180 minutes, and
then heated at 100 to 200.degree. C. under an atmosphere of an
inert gas such as argon or nitrogen to obtain a cesium-oleic acid
solution.
[0079] On the other hand, a solution containing lead (II) bromide
and the organic solvent same as the one described above is
prepared. At this time, 20 to 100 mg of lead (II) bromide is added
to 5 mL of the organic solvent. The obtained solution is dried
under reduced pressure at 90 to 150.degree. C. for 10 to 180
minutes, and then 0.1 to 2 mL of 3-aminopropyltriethoxysilane is
added under an atmosphere of an inert gas such as argon or
nitrogen.
[0080] Then, the above-mentioned cesium-oleic acid solution is
added in a state where the solution containing lead (II) bromide
and 3-aminopropyltriethoxysilane is heated to 140 to 260.degree.
C., and the reaction is carried out by heating and stirring for 1
to 10 seconds. Then, the obtained reaction solution is cooled in an
ice bath. At this time, it is preferable to add 0.1 to 1 mL of the
cesium-oleic acid solution to 5 mL of the solution containing lead
(II) bromide and 3-aminopropyltriethoxysilane. During stirring at
-20 to 30.degree. C., nanocrystals 911 are precipitated, and
3-aminopropyltriethoxysilane and oleic acid are coordinated on the
surfaces of the nanocrystals 911.
[0081] Then, the obtained reaction solution is stirred at room
temperature (10 to 30.degree. C., humidity 5 to 60%) for 5 to 300
minutes in the air, and then 0.1 to 50 mL of ethanol is added to
obtain a suspension. The alkoxysilyl group of
3-aminopropyltriethoxysilane is condensed while stirring at room
temperature in the air to form the surface layer 912 having a
siloxane bond on the surface of the nanocrystal 911.
[0082] By centrifuging the obtained suspension to recover the solid
matter and adding the solid matter to hexane, it is possible to
obtain a parent particle dispersion liquid in which the parent
particles 91 including the surface layer 912 having a siloxane bond
on the surface of the nanocrystal 911 composed of lead cesium
tribromide are dispersed in toluene.
[0083] Next, a method for producing the parent particles 91 without
heating will be described. A method can be mentioned in which a
solution containing a raw material compound for semiconductor
nanocrystals and a solution containing a compound containing Si and
having a reactive group capable of forming a siloxane bond were
mixed in the air, and then the obtained mixture was added to a
large amount of organic solvent which is a poor solvent for the
nanocrystals, thereby precipitating nanocrystals. The amount of the
organic solvent used is preferably 10 to 1000 times the amount of
the semiconductor nanocrystals on a mass basis. Further, the
precipitated nanocrystals have the surface layer 912 having a
siloxane bond formed on the surfaces of the nanocrystals 911, and
the nanocrystals can be obtained by a conventional method such as
centrifugation.
[0084] Specifically, as a solution containing a raw material
compound for semiconductor nanocrystals, for example, a solution
containing lead (II) bromide, methylamine hydrobromide and an
organic solvent is prepared. The organic solvent only needs to be a
good solvent for nanocrystals, but dimethyl sulfoxide,
N,N-dimethylformamide, N-methylformamide, and a mixed solvent
thereof are preferable from the viewpoint of compatibility. At this
time, it is preferable to adjust the addition amount of lead (II)
bromide (II) having 50 to 200 mg and the addition amount of
methylamine hydrobromide having 10 to 100 mg with respect to 10 mL
of the organic solvent.
[0085] On the other hand, as a solution containing a compound
containing Si and having a reactive group capable of forming a
siloxane bond, for example, 3-aminopropyltriethoxysilane, oleic
acid, and a poor solvent are prepared. As the poor solvent,
isopropyl alcohol, toluene, hexane, and the like can be used. At
this time, it is preferable that the amount of each addition is
adjusted so that 3-aminopropyltriethoxysilane is 0.01 to 0.5 mL and
oleic acid is 0.01 to 0.5 mL with respect to 5 mL of the poor
solvent.
[0086] Then, with respect to 0.1 to 5 mL of the above-mentioned
solution containing lead (II) bromide and methylamine hydrobromide,
5 mL of the above-mentioned solution containing
3-aminopropyltriethoxysilane is added at 0 to 60.degree. C. in the
air to obtain a mixture. Immediately after that, the obtained
mixture is added to a large amount of negative solvent, stirred in
the air for 5 to 180 seconds, and then the solid matter is
recovered by centrifugation. When the mixture is added to a large
amount of negative solvent, the nanocrystals 911 are precipitated
and 3-aminopropyltriethoxysilane and oleic acid are coordinated on
the surfaces of the nanocrystals 911. Then, the alkoxysilyl group
of 3-aminopropyltriethoxysilane is condensed while stirring in the
air, and the surface layer 912 having a siloxane bond is formed on
the surface of the nanocrystal 911.
[0087] By adding the recovered solid matter to toluene, it is
possible to obtain a parent particle dispersion in which the parent
particle 91 having the surface layer 912 having a siloxane bond on
the surface of the nanocrystal 911 composed of methylammonium
tribromide crystal is dispersed in toluene.
[0088] <<Step 2 (Polymer Layer Forming Step)>>
[0089] Next, the surface of the parent particle 91 obtained in step
1 is coated with a hydrophobic polymer to form the polymer layer
92. The parent particle 91 is coated with the hydrophobic polymer
layer 92. As a result, the light-emitting particle 90 can be
provided with high stability against oxygen and moisture. Further,
when the ink composition is prepared, the dispersion stability of
the light-emitting particles 90 can be improved.
[0090] Such a polymer layer 92 can be formed by Method I: a method
of coating the surface of the parent particle 91 with a hydrophobic
polymer by adding and mixing the parent particle 91 to a varnish
containing a hydrophobic polymer; Method II: a method of carrying
at least one polymerizable unsaturated monomer that is soluble in a
non-aqueous solvent and becomes insoluble or sparingly soluble
after polymerization, together with a polymer having a
polymerizable unsaturated group soluble in a non-aqueous solvent on
the surface of the parent particle 91, and then polymerizing the
polymer and the polymerizable unsaturated monomer; or the like.
[0091] Note that the hydrophobic polymer in Method I includes a
polymer obtained by polymerizing the polymer and the polymerizable
unsaturated monomer in Method II.
[0092] Among them, the polymer layer 92 is preferably formed by
Method II. According to Method II, the polymer layer 92 having a
uniform thickness can be formed on the parent particle 91 with high
adhesion.
[0093] [Non-Aqueous Solvent]
[0094] The non-aqueous solvent used in this step is preferably an
organic solvent capable of dissolving the hydrophobic polymer, and
more preferably one capable of uniformly dispersing the parent
particles 91. By using such a non-aqueous solvent, the hydrophobic
polymer can be adsorbed on the parent particles 91 and the polymer
layer 92 can be coated very easily. Further, preferably, the
non-aqueous solvent is a low dielectric constant solvent. By using
a low dielectric constant solvent, the hydrophobic polymer can be
strongly adsorbed on the surfaces of the parent particles 91 and
the polymer layer 92 can be coated by simply mixing the hydrophobic
polymer and the parent particles 91 in the non-aqueous solvent.
[0095] The polymer layer 92 thus obtained is difficult to be
removed from the parent particles 91 even if the light-emitting
particles 90 are washed with a solvent. Further, the lower the
dielectric constant of the non-aqueous solvent, the more
preferable. Specifically, the dielectric constant of the
non-aqueous solvent is preferably 10 or less, more preferably 6 or
less, and particularly preferably 5 or less. Preferred non-aqueous
solvents are an aliphatic hydrocarbon solvent and an alicyclic
hydrocarbon solvent, and an organic solvent containing at least one
of the above is preferable.
[0096] Examples of the aliphatic hydrocarbon solvent or the
alicyclic hydrocarbon solvent include n-hexane, n-heptane,
n-octane, cyclopentane, cyclohexane, and the like.
[0097] Further, as long as the effect of the present invention is
not impaired, a mixed solvent obtained by mixing at least one of an
aliphatic hydrocarbon solvent and an alicyclic hydrocarbon solvent
with another organic solvent may be used as the non-aqueous
solvent. Examples of such other organic solvents include aromatic
hydrocarbon solvents such as toluene and xylene; ester solvents
such as methyl acetate, ethyl acetate, n-butyl acetate, and amyl
acetate; ketone solvents such as acetone, methyl ethyl ketone, and
methyl isobutyl ketone, methyl amyl ketones, and cyclohexanone;
alcohol solvents such as methanol, ethanol, n-propanol, i-propanol,
and n-butanol; and the like.
[0098] When used as a mixed solvent, the used amount of at least
one of the aliphatic hydrocarbon solvent and the alicyclic
hydrocarbon solvent is preferably 50% by mass or more, and more
preferably 60% by mass or more.
[0099] [Polymer Containing Polymerizable Unsaturated Group Soluble
in Non-Aqueous Solvent]
[0100] The polymer containing a polymerizable unsaturated group
soluble in a non-aqueous solvent used in this step (hereinafter,
also referred to as "polymer (P)") includes a polymer in which a
polymerizable unsaturated group is introduced into a copolymer of a
polymerizable unsaturated monomer containing an alkyl
(meth)acrylate (A) having an alkyl group having 4 or more carbon
atoms, or a fluorine-containing compound (B, C) having a
polymerizable unsaturated group as a main component, or a
macromonomer composed of a copolymer of a polymerizable unsaturated
monomer containing an alkyl (meth)acrylate (A) having an alkyl
group having 4 or more carbon atoms, or a fluorine-containing
compound (B, C) having a polymerizable unsaturated group as a main
component, and the like.
[0101] Examples of the alkyl (meth)acrylate (A) include n-butyl
(meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl
(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate,
isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl
(meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl
(meth)acrylate. Here, in the present specification,
"(meth)acrylate" means both methacrylate and acrylate. The same
applies to the expression "(meth)acryloyl".
[0102] On the other hand, examples of the fluorine-containing
compound (B) having a polymerizable unsaturated group include a
compound represented by the following general formula (B1).
##STR00001##
[0103] In the above general formula (B1), R.sup.4 is a hydrogen
atom, a fluorine atom, a methyl group, a cyano group, a phenyl
group, a benzyl group or --C.sub.nH.sub.2n-Rf' (where n is an
integer of 1 to 8 and Rf' is any one group of the following
formulas (Rf-1) to (Rf-7)).
[0104] Further, in the above general formula (B1), L is any one
group of the following formulas (L-1) to (L-10).
##STR00002##
(n in the above formulas (L-1), (L-3), (L-5), (L-6), and (L-7) is
an integer of 1 to 8. In the above formulas (L-8), (L-9), and
(L-10), m is an integer of 1 to 8, and n is an integer of 0 to 8.
Rf'' in the above formulas (L-6) and (L-7) is any one group of the
following formulas (Rf-1) to (Rf-7).)
[0105] Further, in the above general formula (B1), Rf is any one
group of the following formulas (Rf-1) to (Rf-7).
[Chem. 3]
--C.sub.nF.sub.2n+1 (Rf-1)
--C.sub.nF.sub.2nH (Rf-2)
--C.sub.nF.sub.2n-1 (Rf-3)
--C.sub.nF.sub.2n-3 (Rf-4)
--C.sub.mF.sub.2mOC.sub.nF.sub.2nCF.sub.3 (Rf-5)
--C.sub.mF.sub.2mOC.sub.nF.sub.2nOC.sub.pF.sub.2pCF.sub.3
(Rf-6)
--CF.sub.2OC.sub.2F.sub.4OC.sub.2F.sub.4OCF.sub.3 (Rf-7)
(n in the above formulas (Rf-1) to (Rf-4) is an integer of 4 to 6.
In the above formula (Rf-5), m is an integer of 1 to 5, n is an
integer of 0 to 4, and the sum of m and n is 4 to 5. In the above
formula (Rf-6), m is an integer of 0 to 4, n is an integer of 1 to
4, p is an integer of 0 to 4, and the sum of m, n, and p is 4 to
5.)
[0106] Further, as preferable specific examples of the compound
represented by the general formula (B1), methacrylates represented
by the following formulas (B1-1) to (B1-7) and acrylates
represented by the following (B1-8) to (B1-15), and the like can be
mentioned. Note that these compounds may be used alone or in
combination of two or more.
##STR00003## ##STR00004##
[0107] Examples of the fluorine-containing compound (C) having a
polymerizable unsaturated group include a poly(perfluoroalkylene
ether) chain and a compound having a polymerizable unsaturated
group at both ends thereof.
[0108] The poly(perfluoroalkylene ether) chain preferably has a
structure in which divalent fluorocarbon groups having 1 to 3
carbon atoms and oxygen atoms are alternately linked.
[0109] Such a poly(perfluoroalkylene ether) chain may contain only
one type of divalent fluorocarbon group having 1 to 3 carbon atoms,
or may contain a plurality of types. Specific examples of the poly
(perfluoroalkylene ether) include a structure represented by the
following general formula (C1).
##STR00005##
[0110] In the above general formula (C1), X is the following
formulas (C1-1) to (C1-5).
[0111] A plurality of X may be the same or different. When
different X are included (when a plurality of types of repeating
units X--O are included), a plurality of the same repeating units
X--O may exist in a random shape or in a block shape.
[0112] Also, n is the number of repeating units and is an integer
of 1 or more.
##STR00006##
[0113] Among them, as the poly(perfluoroalkylene ether) chain, a
structure in which perfluoromethylene represented by the above
formula (C1-1) and perfluoroethylene represented by the above
formula (C1-2) coexist is preferable in that the balance between
the number of fluorine atoms and the number of oxygen atoms is
good, and the polymer (P) is easily entangled with the surface of
the parent particle 91.
[0114] In this case, the abundance ratio of perfluoromethylene
represented by the above formula (C1-1) and perfluoroethylene
represented by the above formula (C1-2) is preferably 1/10 to 10/1,
more preferably 2/8 to 8/2, and even more preferably 3/7 to 7/3 in
the molar ratio [perfluoromethylene (C1-1)/Perfluoroethylene
(C1-2)].
[0115] Further, n in the above general formula (C1) is preferably 3
to 100, and more preferably 6 to 70. Further, the total number of
fluorine atoms contained in the poly(perfluoroalkylene ether) chain
is preferably 18 to 200, and more preferably 25 to 150. In the
poly(perfluoroalkylene ether) chain having such a structure, the
balance between the number of fluorine atoms and the number of
oxygen atoms becomes even better.
[0116] Examples of the raw material compound having a
poly(perfluoroalkylene ether) chain before introducing a
polymerizable unsaturated group at both ends include the following
formulas (C2-1) to (C2-6). Note that "-PFPE-" in the following
formulas (C2-1) to (C2-6) is a poly(perfluoroalkylene ether)
chain.
##STR00007##
[0117] Examples of the polymerizable unsaturated group introduced
at both ends of the poly(perfluoroalkylene ether) chain include
structures represented by the following formulas U-1 to U-5.
##STR00008##
[0118] Among them, the acryloyloxy group represented by the above
formula U-1 or the methacryloyloxy group represented by the above
formula U-2 are preferable in terms of the ease of obtaining and
producing the fluorine-containing compound (C) per se or the ease
of copolymerization with other polymerizable unsaturated
monomers.
[0119] Specific examples of the fluorine-containing compound (C)
include compounds represented by the following formulas (C-1) to
(C-13). Note that "-PFPE-" in the following formulas (C-1) to
(C-13) is a poly(perfluoroalkylene ether) chain.
##STR00009##
[0120] Among them, as the fluorine-containing compound (C),
compounds represented by the above formulas (C-1), (C-2), (C-5), or
(C-6) are preferable in terms of easy industrial production, and a
compound having an acryloyl group at both ends of the
poly(perfluoroalkylene ether) chain represented by the above
formula (C-1), or a compound having a methacryloyl group at both
ends of the poly(perfluoroalkylene ether) chain represented by the
above formula (C-2) is more preferable in that the polymer (P) that
is easily entangled with the surface of the parent particle 91 can
be synthesized.
[0121] Further, examples of compounds other than the alkyl
(meth)acrylate (A) and the fluorine-containing compounds (B, C)
that can be used as the polymerizable unsaturated monomer include
aromatic vinyl compounds such as styrene, .alpha.-methylstyrene,
and p-t-butylstyrene, and vinyltoluene; (meth)acrylate compounds
such as benzyl (meth)acrylate, dimethylamino (meth)acrylate,
diethylamino (meth)acrylate, dibromopropyl (meth)acrylate,
tribromophenyl (meth)acrylate; diester compounds of unsaturated
dicarboxylic acids such as maleic acid, fumaric acid, and itaconic
acid and monovalent alcohols, vinyl ester compounds such as vinyl
benzoate, "Beova" (vinyl ester manufactured by Shell, Netherlands),
and the like.
[0122] These compounds are preferably used as a random copolymer
with an alkyl (meth)acrylate (A) or a fluorine-containing compound
(B, C). Thereby, the solubility of the obtained polymer (P) in a
non-aqueous solvent can be sufficiently enhanced.
[0123] As the compound that can be used as the above-mentioned
polymerizable unsaturated monomer, one type may be used alone, or
two or more types may be used in a combination. Among them, it is
preferable to use alkyl (meth)acrylate (A) having a linear or
branched alkyl group having 4 to 12 carbon atoms, such as n-butyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl
methacrylate.
[0124] The copolymer of a polymerizable unsaturated monomer can be
obtained by polymerizing a polymerizable unsaturated monomer by a
conventional method.
[0125] Further, the polymer (P) can be obtained by introducing a
polymerizable unsaturated group into such a copolymer.
[0126] Examples of the method for introducing the polymerizable
unsaturated group include the following Methods I to IV.
[0127] The method I is a method in which a polymerizable monomer
containing a carboxylic acid group such as acrylic acid and
methacrylic acid, and an amino group-containing polymerizable
monomer such as dimethylaminoethyl methacrylate and
dimethylaminopropylacrylamide are in advance blended as
copolymerization components and copolymerized to obtain a copolymer
having a carboxylic acid group or an amino group, and then the
carboxylic acid group or the amino group is reacted with a monomer
having a glycidyl group and a polymerizable unsaturated group, such
as glycidyl methacrylate.
[0128] Method II is a method in which a hydroxyl group-containing
monomer such as 2-hydroxyethyl methacrylate or 2-hydroxyethyl
acrylate is in advance blended as a copolymerization component and
copolymerized to obtain a copolymer having a hydroxyl group, and
then the hydroxyl group is reacted with a monomer having an
isocyanate group and a polymerizable unsaturated group, such as
isocyanate ethyl methacrylate.
[0129] Method III is a method in which thioglycolic acid is used as
a chain transfer agent during polymerization to introduce a
carboxyl group at the end of the copolymer, and the carboxyl group
is reacted with a monomer having a glycidyl group and a
polymerizable unsaturated group, such as glycidyl methacrylate.
[0130] Method IV is a method in which a carboxyl group-containing
azo initiator such as azobiscyanopentanoic acid is used as a
polymerization initiator to introduce a carboxyl group into the
copolymer, and the carboxyl group is reacted with a monomer having
a glycidyl group and a polymerizable unsaturated group, such as
glycidyl methacrylate.
[0131] Among them, Method I is preferable since it is the
simplest.
[0132] (Polymerizable Unsaturated Monomer that is Soluble in
Non-Aqueous Solvent and Becomes Insoluble or Sparingly Soluble
after Polymerization)
[0133] The polymerizable unsaturated monomers (hereinafter, also
referred to as "monomer (M)") used in this step that is soluble in
a non-aqueous solvent and becomes insoluble or sparingly soluble
after polymerization include, for example, vinyl-based monomers
having no reactive polar group (functional group), vinyl-based
monomers containing amide bond, (meth) acryloyloxyalkyl phosphates,
(meth)acryloyloxyalkyl phosphites, phosphorus atom-containing
vinyl-based monomers, hydroxyl group-containing polymerizable
unsaturated monomers, dialkylaminoalkyl (meth)acrylates, epoxy
group-containing polymerizable unsaturated monomers, isocyanate
group-containing .alpha.,.beta.-ethylenically unsaturated monomers,
alkoxysilyl group-containing polymerizable unsaturated monomers,
carboxyl group-containing .alpha.,.beta.-ethylenically unsaturated
monomers, and the like.
[0134] Specific examples of vinyl-based monomers having no reactive
polar group include, for example, (meth)acrylates such as methyl
(meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and
i-propyl (meth)acrylate, olefins such as (meth)acrylonitrile, vinyl
acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, and
vinylidene fluoride, and the like.
[0135] Specific examples of the vinyl-based monomers containing an
amide bond include, for example, (meth)acrylamide, dimethyl
(meth)acrylamide, N-t-butyl (meth)acrylamide, N-octyl
(meth)acrylamide, diacetone acrylamide,
dimethylaminopropylacrylamide, alkoxylated N-methylolated
(meth)acrylamides, and the like.
[0136] Specific examples of (meth)acryloyloxyalkyl phosphates
include, for example, dialkyl[(meth)acryloyloxyalkyl]phosphates,
(meth)acryloyloxyalkyl acid phosphates, and the like.
[0137] Specific examples of (meth)acryloyloxyalkyl phosphites
include, for example, dialkyl[(meth)acryloyloxyalkyl]phosphites,
(meth)acryloyloxyalkyl acid phosphites, and the like.
[0138] Specific examples of the vinyl-based monomers containing
phosphorus atoms include, for example, alkylene oxide adducts of
the above (meth)acryloyloxyalkyl acid phosphates or
(meth)acryloyloxyalkyl acid phosphites, ester compounds of
vinyl-based monomers containing an epoxy group such as glycidyl
(meth)acrylates and methylglycidyl (meth)acrylate, and phosphoric
acid and phosphorous acid, or acidic esters thereof,
3-chloro-2-acid phosphoxypropyl (meth)acrylate and the like.
[0139] Specific examples of hydroxyl group-containing polymerizable
unsaturated monomers include, for example, hydroxyalkyl esters of
polymerizable unsaturated carboxylic acids such as 2-hydroxyethyl
(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl
(meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl
(meth)acrylate, 4-hydroxybutyl (meth)acrylate,
3-chloro-2-hydroxypropyl (meth)acrylate, di-2-hydroxyethyl
fumarate, mono-2-hydroxyethyl monobutyl fumarate, polypropylene
glycol mono (meth)acrylate, polyethylene glycol mono
(meth)acrylate, or adducts thereof with .epsilon.-caprolactone;
polymerizable unsaturated carboxylic acids such as unsaturated
mono- or dicarboxylic acids, such as (meth)acrylic acid, crotonic
acid, maleic acid, fumaric acid, itaconic acid, and citraconic
acid, and monoesters of dicarboxylic acid and monovalent alcohol;
adducts of various unsaturated carboxylic acids such as adducts of
hydroxyalkyl esters of the polymerizable unsaturated carboxylic
acids with polycarboxylic acid anhydrides (maleic acid, succinic
acid, phthalic acid, hexahydrophthalic acid, tetrahydrophthalic
acid, henzentricarboxylic acid, benzenetetracarboxylic acid, "himic
acid", tetrachlorophthalic acid, dodecynyl succinic acid, and the
like), with monoepoxy compounds, such as monoglycidyl esters of
monovalent carboxylic acid (palm oil fatty acid glycidyl ester,
octyl acid glycidyl ester, etc.), butyl glycidyl ether, ethylene
oxide, propylene oxide, and the like, or adducts thereof with
s-caprolactone; hydroxyvinyl ethers, and the like.
[0140] Specific examples of dialkylaminoalkyl (meth)acrylates
include, for example, dimethylaminoethyl (meth)acrylate,
diethylaminoethyl (meth)acrylate, and the like.
[0141] Specific examples of epoxy group-containing polymerizable
unsaturated monomers include, for example, epoxy group-containing
polymerizable compounds obtained by adding various polyepoxy
compounds having at least two epoxy groups in one molecule to
various unsaturated carboxylic acids such as polymerizable
unsaturated carboxylic acids and equimolar adducts of a hydroxyl
group-containing vinyl monomer and a polycarboxylic acid anhydride
(mono-2-(meth)acryloyloxymonoethyl phthalate, and the like) at an
equimolar ratio, glycidyl (meth)acrylate, (.beta.-methyl) glucidyl
(meth)acrylate, (meth)allyl glucidyl ether, and the like.
[0142] Specific examples of the isocyanate group-containing
.alpha.,.beta.-ethylenically unsaturated monomers include, for
example, equimolar adducts of 2-hydroxyethyl (meth)acrylate and
hexamethylene diisocyanate, and monomers having an isocyanate group
and a vinyl group, such as isocyanate ethyl (meth)acrylate.
[0143] Specific examples of the alkoxysilyl group-containing
polymerizable unsaturated monomers include, for example,
silicon-based monomers such as vinylethoxysilane,
.alpha.-methacryloxypropyltrimethoxysilane, and
trimethylsiloxyethyl (meth)acrylate.
[0144] Specific examples of the carboxyl group-containing
.alpha.,.beta.-ethylenically unsaturated monomers include, for
example, .alpha.,.beta.-ethylenically unsaturated carboxylic acids
such as unsaturated mono- or dicarboxylic acids such as
(meth)acrylic acid, crotonic acid, maleic acid, fumaric acid,
itaconic acid, and citraconic acid, and monoesters of dicarboxylic
acids and monovalent alcohols; adducts of the hydroalkyl esters of
.alpha.,.beta.-ethylenically unsaturated carboxylic acids such as
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate,
3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate,
3-chloro-2-hydroxypropyl (meth)acrylate, di-2-hydrcoxyethyl
fumarate, mono-2-hydroxyethyl-monobutyl fumarate, and polyethylene
glycol mono (meth)acrylate, with anhydrides of polycarboxylic acids
such as maleic acid, succinic acid, phthalic acid,
hexahydrophthalic acid, tetrahydrophthalic acid,
benzenetricarboxylic acid, benzenetetracarboxylic acid, "himic
acid", tetrachlorphthalic acid, and dodecynylsuccinic acid.
[0145] Among them, as the monomer (M), an alkyl (meth)acrylate
having an alkyl group having 3 or less carbon atoms, such as methyl
(meth)acrylate and ethyl (meth)acrylate is preferable.
[0146] Further, when the polymer (P) and the monomer (M) are
polymerized, it is preferable to copolymerize the polymerizable
unsaturated monomer having at least one of functional groups such
as a carboxyl group, a sulfonic acid group, a phosphoric acid
group, a hydroxyl group, and a dimethylamino group. As a result,
the adhesion of the formed polymer (polymer layer 92) to the
surface of the parent particle 91 can be improved by enhancing the
interaction with the siloxane bond.
[0147] Further, in order to prevent or suppress the elution of the
hydrophobic polymer from the obtained light-emitting particles 90,
the hydrophobic polymer (polymer (P)) is preferably
crosslinked.
[0148] Examples of the polyfunctional polymerizable unsaturated
monomer that can be used as a cross-linking component include, for
example, divinylbenzene, ethylene glycol di(meth)acrylate,
diethylene glycol di(meth)acrylate, triethylene glycol
di(meth)acrylate, polyethylene glycol di(meth)acrylate,
1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate,
1,6-hexanediol di(meth)acrylate, neopentyl glycol dimethacrylate,
trimethylolpropan triethoxy tri(meth)acrylate, trimethylolpropan
tri(meth)acrylate, pentaerythritol tri(meth)acrylate,
pentaerythritol tetra (meth)acrylate, dipentaerythritol hexa
(meth)acrylate, and allyl methacrylate.
[0149] Further, other polymerizable unsaturated monomers may be
copolymerized as long as the obtained hydrophobic polymer is not
dissolved in a non-aqueous solvent. Other polymerizable unsaturated
monomers include, for example, the above-mentioned alkyl
(meth)acrylate (A), fluorine-containing compounds (B, C), and
compounds exemplified as polymerizable unsaturated monomers for
polymers (P) that can be used in addition to the above.
[0150] The polymer layer 92 is formed by polymerizing the monomer
(M) in the presence of the parent particles 91, a non-aqueous
solvent, and the polymer (P).
[0151] Preferably, the parent particles 91 and the polymer (P) are
mixed before the polymerization is carried out. For mixing, for
example, a homogenizer, a disper, a bead mill, a paint shaker, a
kneader, a roll mill, a ball mill, an attritor, a sand mill, and
the like can be used.
[0152] In the present invention, the form of the parent particle 91
used is not particularly limited and may be any of slurry, wet
cake, powder, and the like.
[0153] After mixing the parent particle 91 and the polymer (P), the
monomer (M), and the polymerization initiator described later are
further mixed and polymerized to form a polymer layer 92 composed
of the polymer (P) and the monomer (M). As a result, the
light-emitting particles 90 are obtained.
[0154] At this time, the number average molecular weight of the
polymer (P) is preferably 1,000 to 500,000, more preferably 2,000
to 200,000, and even more preferably 3,000 to 100,000. By using the
polymer (P) having the molecular weight in such a range, the
surfaces of the parent particles 91 can be satisfactorily coated
with the polymer layer 92.
[0155] The amount of the polymer (P) used is appropriately set
according to the purpose and is not particularly limited, but in
general, is preferably 0.5 to 50 parts by mass, more preferably 1
to 40 parts by mass, and even more preferably 2 to 35 parts by mass
with respect to 100 parts by mass of the parent particle 91.
[0156] Further, the amount of the monomer (M) used is also
appropriately set according to the purpose and is not particularly
limited, but in general, is preferably 0.5 to 40 parts by mass,
more preferably 1 to 35 parts by mass, and even more preferably 2
to 30 parts by mass with respect to 100 parts by mass of the parent
particle 91.
[0157] The amount of the hydrophobic polymer finally covering the
surface of the parent particle 91 is preferably 1 to 60 parts by
mass, more preferably 2 to 50 parts by mass, and even more
preferably 3 to 40 parts by mass with respect to 100 parts by mass
of the parent particle 91.
[0158] In this case, the amount of the monomer (M) is usually
preferably 10 to 100 parts by mass, more preferably 30 to 90 parts
by mass, even more preferably 50 to 80 parts by mass with respect
to 100 parts by mass of the polymer (P).
[0159] The thickness of the polymer layer 92 is preferably 0.5 to
100 nm, more preferably 0.7 to 50 nm, and even more preferably 1 to
30 nm. If the thickness of the polymer layer 92 is less than 0.5
nm, dispersion stability is not likely to be obtained. If the
thickness of the polymer layer 92 exceeds 100 nm, it is often
difficult to contain the parent particles 91 at a high
concentration. By coating the parent particles 91 with the polymer
layer 92 having such a thickness, the stability of the
light-emitting particles 90 with respect to oxygen and moisture can
be further improved.
[0160] The polymerization of the monomer (M) in the presence of the
parent particles 91, the non-aqueous solvent, and the polymer (P)
can be carried out by a known polymerization method, but is
preferably carried out in the presence of a polymerization
initiator.
[0161] Such polymerization initiators include, for example,
dimethyl-2,2-azobis(2-methylpropionate), azobisisobutyronitrile
(AIBN), 2,2-azobis(2-methylbutyronitrile), benzoyl peroxide,
t-butyl perbenzoate, t-butyl-2-ethylhexanoate, t-butyl
hydroperoxide, di-t-butyl peroxide, cumene hydroperoxide, and the
like. These polymerization initiators may be used alone or in
combination of two or more.
[0162] The polymerization initiator, which is sparingly soluble in
a non-aqueous solvent, is preferably added to a mixed solution
containing the parent particles 91 and the polymer (P) in a state
of being dissolved in the monomer (M).
[0163] Further, the monomer (M) or the monomer (M) in which the
polymerization initiator is dissolved may be added to the mixed
solution having reached the polymerization temperature by a
dropping method to polymerize, but it is stable and preferable to
be added to the mixed solution and mixed sufficiently at room
temperature before the temperature rise, and then the temperature
is raised to polymerize it.
[0164] The polymerization temperature is preferably in the range of
60 to 130.degree. C., and more preferably in the range of 70 to
100.degree. C. When the monomer (M) is polymerized at such a
polymerization temperature, morphological changes (for example,
alteration, crystal growth, and the like) of the nanocrystals 911
can be suitably prevented.
[0165] After the polymerization of the monomer (M), the polymer
that has not been adsorbed on the surfaces of the parent particles
91 is removed to obtain light-emitting particles 90. Examples of
the method for removing the unadsorbed polymer include centrifugal
sedimentation and ultrafiltration. In the centrifugal
sedimentation, the dispersion solution containing the parent
particles 91 and the unadsorbed polymer is rotated at high speed to
settle the parent particles 91 in the dispersion liquid, and the
unadsorbed polymer is separated. In ultrafiltration, the dispersion
solution containing the parent particles 91 and the unadsorbed
polymer is diluted with an appropriate solvent, and the diluted
solution is passed through a filtration membrane having an
appropriate pore size to separate the unadsorbed polymer and the
parent particles 91.
[0166] As described above, the light-emitting particles 90 can be
obtained. The light-emitting particles 90 may be stored in a state
of being dispersed in a dispersion medium or a photopolymerizable
compound (that is, as a dispersion solution), or the dispersion
medium may be removed and stored as powder (aggregate of
light-emitting particles 90 alone).
[0167] <Light-Emitting Particle Dispersion>
[0168] The light-emitting particle dispersion of the present
invention contains light-emitting particles 90 and a dispersion
medium for dispersing the light-emitting particles 90. Note that in
the light-emitting particle dispersion of the present invention, it
is possible to have a configuration containing light-emitting
particles and a dispersion medium for dispersing the light-emitting
particles, using the above-mentioned parent particles 91 as
light-emitting particles.
[0169] <<Dispersion Medium>>
[0170] As the dispersion medium, for example, aromatic solvents
such as toluene, xylene, and methoxybenzene; acetic acid ester
solvents such as ethyl acetate, propyl acetate, butyl acetate,
propylene glycol monomethyl ether acetate, and propylene glycol
monoethyl ether acetate; propionate solvents such as ethoxyethyl
propionate; alcohol solvents such as methanol and ethanol; ether
solvents such as butyl cellosolve, propylene glycol monomethyl
ether, diethylene glycol ethyl ether, and diethylene glycol
dimethyl ether; ketone solvents such as methyl ethyl ketone, methyl
isobutyl ketone, and cyclohexanone; aliphatic hydrocarbon solvents
such as hexane; nitrogen compound solvents such as
N,N-dimethylformamide, .gamma.-butyrolactam,
N-methyl-2-pyrrolidone, aniline, and pyridine; lactone solvents
such as .gamma.-butyrolactone; carbamate esters such as a mixture
of methyl carbamate and ethyl carbamate at a ratio of 48:52, water,
and the like can be mentioned.
[0171] Among them, as the dispersion medium, a non-polar or
low-polarity solvent such as an aromatic solvent, an acetate ester
solvent, a ketone solvent, or an aliphatic hydrocarbon solvent is
preferable and an aromatic solvent or an aliphatic hydrocarbon
solvent is more preferable from the viewpoint of maintaining the
light-emitting properties of the light-emitting particles. When
these solvents are used, two or more types can be used in a
combination.
[0172] <Ink Composition>
[0173] The ink composition of the present invention contains the
light-emitting particles 90, a photopolymerizable compound that
disperses the light-emitting particles 90, and a
photopolymerization initiator. Note that in the ink composition of
the present invention, it is possible to have a configuration
containing the light-emitting particles, a photopolymerizable
compound that disperses the light-emitting particles, and a
photopolymerization initiator, being the above-mentioned parent
particles 91 as light-emitting particles.
[0174] The amount of the light-emitting particles 90 contained in
the ink composition is preferably 10 to 50% by mass, more
preferably 15 to 45% by mass, and even more preferably 20 to 40% by
mass. By setting the amount of the light-emitting particles 90
contained in the ink composition in the above range, the ejection
stability of the ink composition can be further improved when the
ink composition is ejected by the inkjet printing method. In
addition, the light-emitting particles 90 are less likely to
agglomerate with each other, and the external quantum efficiency of
the obtained light-emitting layer (light conversion layer) can be
increased.
[0175] <<<Photopolymerizable Compound>>
[0176] The photopolymerizable compound contained in the ink
composition of the present invention is preferably a photoradical
polymerizable compound that polymerizes by irradiation with light
and may be a photopolymerizable monomer or oligomer. These are used
with photopolymerization initiators. One type of photopolymerizable
compound may be used alone or two or more types may be used in a
combination.
[0177] Examples of the photoradical polymerizable compound include
(meth)acrylate compounds. The (meth)acrylate compound may be a
monofunctional (meth)acrylate having one (meth)acryloyl group or
may be a polyfunctional (meth)acrylate having a plurality of
(meth)acryloyl groups.
[0178] Preferably, monofunctional (meth)acrylate and polyfunctional
(meth)acrylate are used in a combination from the viewpoint of
excellent fluidity when preparing an ink composition, excellent
ejection stability, and suppressing deterioration of smoothness due
to curing shrinkage during production of a light-emitting particle
coating film.
[0179] The monofunctional (meth)acrylate includes, for example,
methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,
butyl (meth)acrylate, amyl (meth)acrylate, 2-ethylhexyl
(meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl
(meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate,
cyclohexyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl
(meth)acrylate, phenoxyethyl (meth)acrylate, nonylphenoxyethyl
(meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl
(meth)acrylate, diethylaminoethyl (meth)acrylate, isobornyl
(meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl
(meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate,
2-hydroxy-3-phenoxypropyl (meth)acrylate, tetrahydrofurfuryl
(meth)acrylate, 2-hydroxyethyl (meth)acrylate, benzyl
(meth)acrylate, phenylbenzyl (meth)acrylate,
mono(2-acryloyloxyethyl) succinate,
N-[2-(acryloyloxy)ethyl]phthalimide, N-[2-(acryloyloxy)ethyl]
tetrahydrophthalimide, and the like.
[0180] The polyfunctional (meth)acrylate may be a bifunctional
(meth)acrylate, a trifunctional (meth)acrylate, a tetrafunctional
(meth)acrylate, a pentafunctional (meth)acrylate, a hexafunctional
(meth)acrylate, or the like, and may be, for example,
di(meth)acrylate in which two hydroxyl groups of a diol compound
are substituted with (meth)acryloyloxy group, di- or
tri(meth)acrylate in which two or three hydroxyl groups of a triol
compound are substituted with (meth)acryloyloxy group, and the
like.
[0181] Specific examples of the bifunctional (meth)acrylate
include, for example, 1,3-butylene glycol di((meth)acrylate,
1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate,
3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,8-octanediol
di(meth)acrylate, 1,9-nonandiol di(meth)acrylate,
tricyclodecanedimethanol di(meth)acrylate, ethylene glycol
di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene
glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate,
tripropylene glycol di(meth)acrylate, polypropylene glycol
di(meth)acrylate, neopentylglycol hydroxypivalic acid ester
diacrylate, and di(meth)acrylate in which two hydroxyl groups of
tris(2-hydroxyethyl) isocyanurate are substituted with
(meth)acryloyloxy group, di(meth)acrylate in which two hydroxyl
groups of the diol obtained by adding 4 mol or more of ethylene
oxide or propylene oxide to 1 mol of neopentyl glycol are
substituted with (meth)acryloyloxy group, di(meth)acrylate in which
two hydroxyl groups of the diol obtained by adding 2 mol of
ethylene oxide or propylene oxide to 1 mol of bisphenol A are
substituted with (meth)acryloyloxy group, di(meth)acrylate in which
two hydroxyl groups of the triol obtained by adding 3 mol or more
of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane
are substituted with (meth)acryloyloxy group, di(meth)acrylate in
which two hydroxyl groups of the diol obtained by adding 4 mol or
more of ethylene oxide or propylene oxide to 1 mol of bisphenol A
are substituted with (meth)acryloyloxy group, and the like.
[0182] Specific examples of the trifunctional (meth)acrylate
include, for example, trimethylolpropane tri(meth)acrylate,
glycerin triacrylate, pentaerythritol tri(meth)acrylate,
tri(meth)acrylate in which the three hydroxyl groups of the triol
obtained by adding 3 mol or more of ethylene oxide or propylene
oxide to 1 mol of trimethylolpropane are substituted with
(meth)acryloyloxy group, and the like.
[0183] Specific examples of the tetrafunctional (meth)acrylate
include pentaerythritol tetra (meth)acrylate and the like.
[0184] Specific examples of the pentafunctional (meth)acrylate
include dipentaerythritol penta(meth)acrylate.
[0185] Specific examples of the hexafunctional (meth)acrylate
include dipentaerythritol hexa(meth)acrylate.
[0186] The polyfunctional (meth)acrylate may be a poly
(meth)acrylate in which a plurality of hydroxyl groups of
dipentaerythritol such as dipentaerythritol hexa(meth)acrylate are
substituted with (meth)acryloyloxy group.
[0187] The (meth)acrylate compound may be an ethylene
oxide-modified phosphoric acid (meth)acrylate, an ethylene
oxide-modified alkyl phosphoric acid (meth)acrylate, or the like,
which has a phosphoric acid group.
[0188] In the ink composition of the present invention, when the
curable component is composed of a photopolymerizable compound only
or as a main component, it is more preferable to use, as the
photopolymerizable compound as described above, a bifunctional or
higher polyfunctional photopolymerizable compound having two or
more polymerizable functional groups in one molecule as an
essential component since the durability (strength, heat
resistance, and the like) of the cured product can be further
enhanced.
[0189] The amount of the photopolymerizable compound contained in
the ink composition is preferably 40 to 80% by mass, more
preferably 45 to 75% by mass, and even more preferably 50 to 70% by
mass. By setting the amount of the photopolymerizable compound
contained in the ink composition in the above range, the dispersed
state of the light-emitting particles 90 in the obtained
light-emitting layer (light conversion layer) becomes good, and
thus the external quantum efficiency can be further improved.
[0190] <<Photopolymerization Initiator>>
[0191] The photopolymerization initiator in the ink composition
used in the present invention is preferably at least one selected
from the group consisting of alkylphenone-based compounds,
acylphosphine oxide-based compounds, and oxime ester-based
compounds.
[0192] Examples of the alkylphenone-based photopolymerization
initiator include compounds represented by the formula (b-1).
##STR00010##
[0193] (In the formula, R1a represents a group selected from the
following formulas (R.sup.1a-1) to (R.sup.1a-6), and R.sup.2a,
R.sup.2b, and R.sup.2c independently represent a group selected
from the following formulas (R.sup.2-1) to (R.sup.2-7).)
##STR00011##
[0194] As a specific example of the compound represented by the
above formula (b-1), the compounds represented by the following
formulas (b-1-1) to (b-1-6) are preferable, and the compounds
represented by the following formulas (b-1-1), (b-1-5), or (b-1-6)
are more preferable.
##STR00012##
[0195] Examples of the acylphosphine oxide-based
photopolymerization initiator include the compounds represented by
the formula (b-2).
##STR00013##
[0196] (In the formula, R.sup.24 represents an alkyl group, an aryl
group, or a heterocyclic group, and R.sup.25 and R.sup.26
independently represent an alkyl group, an aryl group, a
heterocyclic group, or an alkanoyl group, where these groups may be
substituted with an alkyl group, a hydroxyl group, a carboxyl
group, a sulfone group, an aryl group, an alkoxy group or an
arylthio group.)
[0197] As a specific example of the compound represented by the
above formula (b-2), the compounds represented by the following
formulas (b-2-1) to (b-2-5) are preferable, and the compounds
represented by the following formula (b-2-1) or the formula (b-2-5)
are more preferable.
##STR00014##
[0198] Examples of the oxime ester-based photopolymerization
initiator include the compounds represented by the following
formula (b-3-1) or formula (b-3-2).
##STR00015##
[0199] (In the formula, R.sup.27 to R.sup.31 independently
represent a hydrogen atom, a cyclic, linear, or branched alkyl
group having 1 to 12 carbon atoms, or a phenyl group, where each
alkyl group and phenyl group may be substituted with a substituent
selected from the group consisting of a halogen atom, an alkoxyl
group having 1 to 6 carbon atoms, and a phenyl group, where X.sup.1
represents an oxygen atom or a nitrogen atom, X.sup.2 represents an
oxygen atom or an NR, and R represents an alkyl group having 1 to 6
carbon atoms.)
[0200] As specific examples of the compounds represented by the
above formulas (b-3-1) and (b-3-2), the compounds represented by
the following formulas (b-3-1-1) to (b-3-1-2) and the following
formulas (b-3-2-1) to (b-3-2-2) are preferable, and the compounds
represented by the following formulas (b-3-1-1), (b-3-2-1), or
(b-3-2-2) are more preferable.
##STR00016##
[0201] The blending amount of the photopolymerization initiator is
preferably 0.05 to 10% by mass, more preferably 0.1 to 8% by mass,
and even more preferably 1 to 6% by mass, based on the total amount
of the photopolymerizable compounds contained in the ink
composition. Note that the photopolymerization initiator can be
used alone or in combination of two or more. An ink composition
containing a photopolymerization initiator in such an amount
maintains sufficient photosensitivity during photocuring, and
crystals of the photopolymerization initiator are less likely to
precipitate when the coating film is dried, and thus, the
deterioration of the physical properties of the coating film can be
suppressed.
[0202] When dissolving the photopolymerization initiator in the ink
composition, it is preferable to dissolve the photopolymerization
initiator in the photopolymerizable compound in advance before
use.
[0203] In order to dissolve in the photopolymerizable compound, it
is preferable to uniformly dissolve the photopolymerization
initiator by adding the photopolymerization initiator while
stirring the photopolymerizable compound so that the reaction due
to heat is not started.
[0204] The dissolution temperature of the photopolymerization
initiator may be appropriately adjusted in consideration of the
solubility of the photopolymerization initiator used in the
photopolymerizable compound and the thermal polymerizable property
of the photopolymerizable compound, but the temperature is
preferably 10 to 50.degree. C., more preferably 10 to 40.degree.
C., and even more preferably 10 to 30.degree. C. from the viewpoint
of not starting the polymerization of the photopolymerizable
compound.
[0205] The ink composition used in the present invention may
contain other components other than the light-emitting particles
90, the photopolymerizable compound, and the photopolymerization
initiator as long as the effects of the present invention are not
impaired. Examples of such other components include polymerization
inhibitors, antioxidants, dispersants, leveling agents, chain
transfer agents, dispersion aids, thermoplastic resins,
sensitizers, light scattering particles, and the like.
[0206] <<Polymerization Inhibitor>>
[0207] The polymerization inhibitors include, for example, phenolic
compounds such as p-methoxyphenol, cresol, t-butylcatechol,
3,5-di-t-butyl-4-hydroxytoluene, 2,2'-methylene
bis(4-methyl-6-t-butylphenol), 2,2'-methylene
bis(4-ethyl-6-t-butylphenol),
4,4'-thiobis(3-methyl-6-t-butylphenol), 4-methoxy-1-naphthol, and
4,4'-dialkoxy-2,2'-bi-1-naphthol; quinone compounds such as
hydroquinone, methylhydroquinone, tert-butylhydroquinone,
p-benzoquinone, methyl-p-benzoquinone, tert-butyl-p-benzoquinone,
2,5-diphenylbenzoquinone, 2-hydroxy-1,4-naphthoquinone,
1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, anthraquinone,
and diphenoquinone; amine-based compounds such as
p-phenylenediamine, 4-aminodiphenylamine,
N,N'-diphenyl-p-phenylenediamine,
N-i-propyl-N'-phenyl-p-phenylenediamine,
N-(1.3-dimethylbutyl)-N'-phenyl-p-phenylenediamine,
N,N'-di-2-naphthyl-p-phenylenediamine, diphenylamine,
N-phenyl-.beta.-naphthylamine, 4,4'-dicumyl-diphenylamine, and
4,4'-dioctyl-diphenylamine; thioether-based compounds such as
phenothiazine, and distearylthiodipropionate; N-oxyl compounds such
as 2,2,6,6-tetramethylpiperidine-1-oxyl free radical,
2,2,6,6-tetramethylpiperidine,
4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical; nitroso
compounds such as N-nitrosodiphenylamine,
N-nitrosophenylnaphthylamine, N-nitrosodinaphthylamine,
p-nitrosophenol, nitrosobenzene, p-nitrosodiphenylamine,
.alpha.-nitroso-.beta.-naphthol, N,N-dimethyl-p-nitrosoaniline,
p-nitrosodiphenylamine, p-nitrosodimethylamine,
p-nitroso-N,N-diethylamine, N-nitrosoethanolamine,
N-nitroso-di-n-butylamine, N-nitroso-N-n-butyl-4-butanolamine,
N-nitroso-diisopropanolamine, N-nitroso-N-ethyl-4-butanolamine,
5-nitroso-8-hydroxyquinoline, N-nitrosomorpholin,
N-nitroso-N-phenylhydroxylamine ammonium salt (manufactured by Fuji
Film Wako Pure Chemical Industries, Ltd., "Q-1300"), nitroso
benzene, 2,4,6-tri-tert-butylnitronbenzene,
N-nitroso-N-methyl-p-toluenesulfonamide, N-nitroso-N-ethylurethane,
N-nitroso-N-n-propylurethane, 1-nitroso-2-naphthol,
2-nitroso-1-naphthol, sodium 1-nitroso-2-naphthol-3,6-sulfonate,
sodium 2-nitroso-1-naphthol-4-sulfonate,
2-nitroso-5-methylaminophenol hydrochloride,
2-nitroso-5-methylaminophenol hydrochloride, Q-1301 (manufactured
by Fuji Film Wako Pure Chemical Industries, Ltd.), and the
like.
[0208] The amount of the polymerization inhibitor added is
preferably 0.01 to 1.0% by mass, and more preferably 0.02 to 0.5%
by mass, based on the total amount of the photopolymerizable
compounds contained in the ink composition.
[0209] <<Antioxidant>>
[0210] The antioxidant includes, for example, pentaerythritol
tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate
("IRGANOX1010"),
thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate
("IRGANOX1035"), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)
propionate ("IRGANOX1076"), "IRGANOX1135", "IRGANOX1330", 4,6-bis
(octylthiomethyl)-o-cresol ("IRGANOX1520L"), "IRGANOX1726",
"IRGANOX245", "IRGANOX259", "IRGANOX3114", "IRGANOX3790",
"IRGANOX5057", "IRGANOX565", (all above manufactured by BASF Co.,
Ltd.); "ADEKA STAB AO-20", "ADEKA STAB AO-30", "ADEKA STAB AO-40",
"ADEKA STAB AO-50", "ADEKA STAB AO-60", "ADEKA STAB AO-80" (all
above, manufactured by ADEKA Co., Ltd.); "JP-360", "JP-308E",
"JPE-10" (all above, manufactured by Johoku Chemical Industry Co.,
Ltd.); "SIMILIZER BHT", "SIMILIZER BBM-S", "SIMILIZER GA-80" (all
above, manufactured by Sumitomo Chemical Co., Ltd.), and the
like.
[0211] The amount of the antioxidant added is preferably 0.01 to
2.0% by mass, and more preferably 0.02 to 1.0% by mass, based on
the total amount of the photopolymerizable compounds contained in
the ink composition.
[0212] <<Dispersant>>
[0213] The dispersant is not particularly limited as long as it is
a compound capable of improving the dispersion stability of the
light-emitting particles 90 in the ink composition. Dispersants are
classified into low-molecular dispersants and high-molecular
dispersants.
[0214] In the present specification, "low-molecular" means a
molecule having the weight average molecular weight (Mw) of 5,000
or less, and "high-molecular" means a molecule having the weight
average molecular weight (Mw) of more than 5,000. Note that in the
present specification, the value measured by gel permeation
chromatography (GPC) using polystyrene as a standard substance can
be adopted as the "weight average molecular weight (Mw)".
[0215] The low-molecular dispersants include, for example, oleic
acid; phosphorous atom-containing compounds such as triethyl
phosphate, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide),
hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and
octylphosphinic acid (OPA); nitrogen atom-containing compounds such
as oleylamine, octylamine, trioctylamine, and hexadecylamine;
sulfur atom-containing compounds such as 1-decanethiol,
octanethiol, dodecanethiol, and amylsulfide; and the like.
[0216] On the other hand, the high-molecular dispersants include,
for example, acrylic resins, polyester resins, polyurethane resins,
polyamide resins, polyether resins, phenol resins, silicone resins,
polyurea resins, amino resins, polyamine resins (polyethyleneimine,
polyallylamine, and the like), epoxy resins, polyimide resins,
natural rosins such as wood rosins, gum rosins, tall oil rosin,
modified rosins such as polymerized rosins, disproportionated
rosins, hydrogenated rosins, oxide rosins, maleinized rosins, rosin
amines, lime rosins, rosin alkylene oxide adducts, rosin alkyd
adducts, rosin derivatives such as rosin modified phenols, and the
like.
[0217] Note that as commercially available high-molecular
dispersants, for example, DISPERBYK series manufactured by
BYK-Chemie, TEGO Dispers series manufactured by Evonik, EFKA series
manufactured by BASF, SOLSPERSE series manufactured by Lubrizol
Japan, AJISPER series manufactured by Ajinomoto Fine Techno Co.,
Ltd., DISPARLON series manufactured by Kusumoto Kasei, FLOWLEN
series manufactured by Kyoeisha Chemical Co., Ltd., and the like
can be used.
[0218] The blending amount of the dispersant is preferably 0.05 to
10 parts by mass, and more preferably 0.1 to 5 parts by mass with
respect to 100 parts by mass of the light-emitting particles
90.
[0219] <<Leveling Agent>>
[0220] The leveling agent is not particularly limited, but a
compound capable of reducing film thickness unevenness when forming
a thin film of the light-emitting particles 90 is preferable.
[0221] Such leveling agents include, for example, alkyl
carboxylates, alkyl phosphates, alkyl sulfonates, fluoroalkyl
carboxylates, fluoroalkyl phosphates, fluoroalkyl sulfonates,
polyoxyethylene derivatives, fluoroalkyl ethylene oxide
derivatives, polyethylene glycol derivatives, alkylammonium salts,
fluoroalkylammonium salts, and the like.
[0222] Specific examples of the leveling agent include, for
example, "Megaface F-114", "Megaface F-251", "Megaface F-281",
"Megaface F-410", "Megaface F-430", "Megaface F-444", "Megaface
F-472SF", "Megaface F-477", "Megaface F-510", "Megaface F-511",
"Megaface F-552", "Megaface F-553", "Megaface F-554", "Megaface
F-555", "Megaface F-556", "Megaface F-557", "Megaface F-558",
"Megaface F-559", "Megaface F-560", "Megaface F-561", "Megaface
F-562", "Megaface F-563", "Megaface F-565", "Megaface F-567",
"Megaface F-568", "Megaface F-569", "Megaface F-570", "Megaface
F-571", "Megaface R-40", "Megaface R-41", "Megaface R-43",
"Megaface R-94", "Megaface RS-72-K", "Megaface RS-75", "Megaface
RS-76-E", "Megaface RS-76-NS", "Megaface RS-90", "Megaface
EXP.TF-1367", "Megaface EXP.TF1437", "Megaface EXP.TF1537",
"Megaface EXP.TF-2066" (all above, manufactured by DIC Corporation)
and the like.
[0223] Other specific examples of the leveling agent include, for
example, "Ftergent 100", "Ftergent 100C", "Ftergent 110", "Ftergent
150", "Ftergent 150CH", "Ftergent 100A-K", "Ftergent 300",
"Ftergent 310", "Ftergent 320", "Ftergent 400SW", "Ftergent 251",
"Ftergent 215M", "Ftergent 212M", "Ftergent 215M", "Ftergent 250",
"Ftergent 222F", "Ftergent 212D", "FTX-218", "Ftergent 209F",
"Ftergent 245F", "Ftergent 208G", "Ftergent 240G", "Ftergent 212P",
"Ftergent 220P", "Ftergent 228P", "DFX-18", "Ftergent 601AD",
"Ftergent 602A", "Ftergent 650A", "Ftergent 750FM", "FTX-730FM",
"Ftergent 730FL", "Ftergent 710FS", "Ftergent 710FM", "Ftergent
710FL", "Ftergent 750LL", "FTX-730LS", "Ftergent 730LM" (all above,
manufactured by Neos Co., Ltd.), and the like.
[0224] Other specific examples of the leveling agent include, for
example, "BYK-300", "BYK-302", "BYK-306", "BYK-307", "BYK-310",
"BYK-315", "BYK-320", "BYK-322", "BYK-323", "BYK-325", "BYK-330",
"BYK-331", "BYK-333", "BYK-337", "BYK-340", "BYK-344", "BYK-370",
"BYK-375", "BYK-377", "BYK-350", "BYK-352", "BYK-354", "BYK-355",
"BYK-356", "BYK-358N", "BYK-361N", "BYK-357", "BYK-390", "BYK-392",
"BYK-UV3500", "BYK-UV3510", "BYK-UV3570", "BYK-Silclean 3700" (all
above, manufactured by BYK USA), and the like.
[0225] Other specific examples of the leveling agent include, for
example, "TEGO Rad2100", "TEGO Rad2011", "TEGO Rad2200N", "TEGO
Rad2250", "TEGO Rad2300", "TEGO Rad2500", "TEGO Rad2600", "TEGO
Rad2650", "TEGO Rod2700", "TEGO Flow300", "TEGO Flow370", "TEGO
Flow425", "TEGO Flow ATF2", "TEGO Flow ZFS460", "TEGO Glide100",
"TEGO Glide110", "TEGO Glide130", "TEGO Glide410", "TEGO Glide411",
"TEGO Glide415", "TEGO Glide432", "TEGO Glide440", "TEGO Glide450",
"TEGO Glide482", "TEGO Glide A115", "TEGO Glide B1484", "TEGO Glide
ZG400", "TEGO Twin4000", "TEGO Twin4100", "TEGO Twin4200", "TEGO
Wet240", "TEGO Wet250", "TEGO Wet260", "TEGO Wet265", "TEGO
Wet270", "TEGO Wet280", "TEGO Wet500", "TEGO Wet505", "TEGO
Wet510", "TEGO Wet520", "TEGO Wet KL245" (all above, manufactured
by Evonik Industries, Ltd.), and the like.
[0226] Other specific examples of the leveling agent include, for
example, "FC-4430", "FC-4432" (all above, manufactured by 3M Japan
Ltd.), "UNIDYNE NS" (all above, manufactured by Daikin Industries,
Ltd.), "SURFLON S-241", "SURFLON S-242", "SURFLON S-243", "SURFLON
S-420", "SURFLON S-611", "SURFLON S-651", "SURFLON S-386" (all
above, manufactured by AGC Seimi Chemical Co., Ltd.), and the
like.
[0227] Other specific examples of the leveling agent include, for
example, "DISPARLON OX-880EF", "DISPARLON OX-881", "DISPARLON
OX-883", "DISPARLON OX-77EF", "DISPARLON OX-710", "DISPARLON 1922",
"DISPARLON 1927", "DISPARLON 1958", "DISPARLON P-410EF", "DISPARLON
P-420", "DISPARLON P-425", "DISPARLON PD-7", "DISPARLON 1970",
"DISPARLON 230" "DISPARLON LF-1980", "DISPARLON LF-1982",
"DISPARLON LF-1983", "DISPARLON LF-1084", "DISPARLON LF-1985",
"DISPARLON LHP-90", "DISPARLON LHP-91", "DISPARLON LHP-95",
"DISPARLON LHP-96", "DISPARLON OX-715", "DISPARLON 1930N",
"DISPARLON 1931", "DISPARLON 1933", "DISPARLON 1934", "DISPARLON
1711EF", "DISPARLON 1751N", "DISPARLON 1761", "DISPARLON LS-009",
"DISPARLON LS-001", "DISPARLON LS-050" (all above, manufactured by
Kusumoto Kasei Co., Ltd.), and the like.
[0228] Other specific examples of the leveling agent include, for
example, "PF-151N", "PF-636", "PF-6320", "PF-656", "PF-6520",
"PF-652-NF", "PF-3320" (all above, manufactured by OMNOVA
SOLUTIONS), "POLYFLOW No. 7", "POLYFLOW No. 50E", "POLYFLOW No.
50EHF", "POLYFLOW No. 54N", "POLYFLOW No. 75", "POLYFLOW No. 77",
"POLYFLOW No. 85", "POLYFLOW No. 85HF", "POLYFLOW No. 90",
"POLYFLOW No. 90D-50", "POLYFLOW No. 95", "POLYFLOW No. 99C",
"POLYFLOW KL-400K", "POLYFLOW KL-400HF", "POLYFLOW KL-401",
"POLYFLOW KL-402", "POLYFLOW KL-403", "POLYFLOW KL-404", "POLYFLOW
KL-100", "POLYFLOW LE-604", "POLYFLOW KL-700", "FLOWLEN AC-300",
"FLOWLEN AC-303", "FLOWLEN AC-324", "FLOWLEN AC-326F", "FLOWLEN
AC-530", "FLOWLEN AC-903", "FLOWLEN AC-903HF", "FLOWLEN AC-1160",
"FLOWLEN AC-1190", "FLOWLEN AC-2000", "FLOWLEN AC-2300C", "FLOWLEN
AO-82", "FLOWLEN AO-98", "FLOWLEN AO-108" (all above, manufactured
by Kyoeisha Chemical Co., Ltd.), and the like.
[0229] Further, other specific examples of the leveling agent
include, for example, "L-7001", "L-7002", "8032ADDITIVE",
"57ADDTIVE", "L-7064", "FZ-2110", "FZ-2105", "67ADDTIVE",
"8616ADDTIVE" (all above, manufactured by Toray Dow Silicone Co.,
Ltd.) and the like.
[0230] The amount of the leveling agent added is preferably 0.005
to 2% by mass, and more preferably 0.01 to 0.5% by mass, based on
the total amount of the photopolymerizable compounds contained in
the ink composition.
[0231] <<Chain Transfer Agent>>
[0232] The chain transfer agent is a component used for the purpose
of further improving the adhesion of the ink composition to the
substrate.
[0233] The chain transfer agents include, for example, aromatic
hydrocarbons; halogenated hydrocarbons such as chloroform, carbon
tetrachloride, carbon tetrabromide, and bromotrichloromethane;
mercaptan compounds such as octyl mercaptan, n-butyl mercaptan,
n-pentyl mercaptan, n-hexadecyl mercaptan, n-tetradecylmer,
n-dodecyl mercaptan, t-tetradecyl mercaptan, and t-dodecyl
mercaptan; thiol compounds such as hexanedithiol, decandithiol,
1,4-butanediol bisthiopropionate, 1,4-butanediol bisthioglycolate,
ethylene glycol bisthioglycolate, ethylene glycol
bisthiopropionate, trimethylolpropane tristhioglycolate,
trimethylolpropane tristhiopropionate, trimethylolpropane tris
(3-mercaptobutyrate), pentaerythritol tetrakisthioglycolate,
pentaerythritol tetrakisthiopropionate, tris (2-hydroxyethyl)
trimercaptopropionate isocyanurate, 1,4-dimethylmercaptobenzene,
2,4,6-trimercapto-s-triazine,
2-(N,N-dibutylamino)-4,6-dimercapto-s-triazine; sulfide compounds
such as dimethylxanthogen disulfide, diethylxantogen disulfide,
diisopropylxantogen disulfide, tetramethyithiuram disulfide,
tetraethylthiuram disulfide, tetrabutylthiuram disulfide;
N,N-dimethylaniline, N,N-divinylaniline, pentaphenylethane,
.alpha.-methylstyrene dimer, acrolein, allyl alcohol, terpinolene,
.alpha.-terpinene, .gamma.-terpinene, and dipentene, but
2,4-diphenyl-4-methyl-1-pentene and thiol compounds are
preferable.
[0234] As a specific example of the chain transfer agent, for
example, compounds represented by the following general formulas
(9-1) to (9-12) are preferable.
##STR00017## ##STR00018##
[0235] In the formula, R.sup.95 represents an alkyl group having 2
to 18 carbon atoms, where the alkyl group may be a straight chain
or a branched chain, and in one or more methylene groups in the
alkyl group, the oxygen atom and the sulfur atom may be substituted
with an oxygen atom, a sulfur atom, --CO--, --OCO--, --COO-- or
--CH.dbd.CH-- without being directly bonded to each other.
[0236] R.sup.96 represents an alkylene group having 2 to 18 carbon
atoms, where in one or more methylene groups in the alkylene group,
the oxygen atom and the sulfur atom may be substituted with an
oxygen atom, a sulfur atom, --CO--, --OCO--, --COO-- or
--CH.dbd.CH-- without being directly bonded to each other.
[0237] The amount of the chain transfer agent added is preferably
0.1 to 10% by mass, and more preferably 1.0 to 5% by mass, based on
the total amount of the photopolymerizable compounds contained in
the ink composition.
[0238] <<Dispersion Aid>>
[0239] The dispersion aids include, for example, organic pigment
derivatives such as phthalimide methyl derivatives, phthalimide
sulfonic acid derivatives, phthalimide N-(dialkylamino)methyl
derivatives, phthalimide N-(dialkylaminoalkyl) sulfonic acid amide
derivatives. These dispersion aids may be used alone or in
combination of two or more.
[0240] <<Thermoplastic Resin>>
[0241] The thermoplastic resins include, for example, urethane
resins, acrylic resin, polyamide resins, polyimide resins, styrene
maleic acid resins, styrene maleic anhydride resins, polyester
acrylate resins, and the like.
[0242] <<Sensitizer>>
[0243] As the sensitizer, amines that do not cause an addition
reaction with the photopolymerizable compound can be used. Such
sensitizers include, for example, trimethylamine,
methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone,
ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate,
N,N-dimethylbenzylamine, 4,4'-bis(diethylamino)benzophenone, and
the like.
[0244] <<Light-Scattering Particles>>
[0245] The light-scattering particles are preferably, for example,
optically inactive inorganic fine particles. The light-scattering
particles can scatter the light from the light source unit
irradiating the light-emitting layer (light conversion layer).
[0246] Materials constituting the light-scattering particles
include, for example, metals per se such as tungsten, zirconium,
titanium, platinum, bismuth, rhodium, palladium, silver, tin,
platinum, and gold; metal oxides such as silica, barium sulfate,
barium carbonate, calcium carbonate, talc, titanium oxide, clay,
kaolin, barium sulfate, barium carbonate, calcium carbonate,
alumina white, titanium oxide, magnesium oxide, barium oxide,
aluminum oxide, bismuth oxide, zirconium oxide, and zinc oxide;
metal carbonates such as magnesium carbonate, barium carbonate,
bismuth hypocarbonate, and calcium carbonate; metal hydroxides such
as aluminum hydroxide; composite oxides such as barium zirconate,
calcium zirconate, calcium titanate, barium titanate, strontium
titanate, and metal salts such as bismuth hyponitrate, and the
like.
[0247] Among them, a material constituting the light-scattering
particles contains preferably at least one selected from the group
consisting of titanium oxide, alumina, zirconium oxide, zinc oxide,
calcium carbonate, barium sulfate, and silica, and more preferably
at least one selected from the group consisting of titanium oxide,
barium sulfate, and calcium carbonate, from the viewpoint of better
excellency in the effect of reducing leaked light.
[0248] <Preparation Method of Ink Composition>
[0249] The ink composition as described above can be prepared by
dispersing the light-emitting particles 90 in a solution in which a
photopolymerizable compound, a photopolymerization initiator and
the like are mixed.
[0250] Dispersion of the light-emitting particles 90 can be
performed by using, for example, a disperser such as a ball mill, a
sand mill, a bead mill, a three-roll mill, a paint conditioner, an
attritor, a dispersion stirrer, and an ultrasonic wave.
[0251] The viscosity of the ink composition used in the present
invention is preferably in the range of 2 to 20 mPa-s, more
preferably in the range of 5 to 15 mPa-s, and even more preferably
in the range of 7 to 12 mPa-s, from the viewpoint of ejection
stability during inkjet printing. In this case, since the meniscus
shape of the ink composition in the ink ejection hole of the
ejection head is stable, the ejection control of the ink
composition (for example, the control of the ejection amount and
the ejection timing) becomes easy. In addition, the ink composition
can be smoothly ejected from the ink ejection holes. The viscosity
of the ink composition can be measured by, for example, an E-type
viscometer.
[0252] Further, the surface tension of the ink composition is
preferably a surface tension suitable for the inkjet printing
method. The specific value of the surface tension is preferably in
the range of 20 to 40 mN/m, and more preferably in the range of 25
to 35 mN/m. By setting the surface tension in the above range, it
is possible to suppress the occurrence of flight bending of the
droplets of the ink composition. Note that the flight bending means
that when the ink composition is ejected from the ink ejection
holes, the landing position of the ink composition deviates from
the target position by 30 .mu.m or more.
[0253] <Light-Emitting Element>
[0254] FIG. 2 is a cross-sectional view showing an embodiment of
the light-emitting element of the present invention, and FIGS. 3
and 4 are schematic views showing the configuration of an active
matrix circuit, respectively.
[0255] Note that in FIG. 2, for convenience, the dimensions of each
part and ratios thereof are exaggerated and may differ from the
actual ones. Further, the materials, dimensions, and the like shown
below are examples, and the present invention is not limited
thereto, and can be appropriately changed without changing the gist
thereof.
[0256] In the following, for convenience of explanation, the upper
side of FIG. 2 is referred to as "upper side" or "upper", and the
upper side is referred to as "lower side" or "lower". Further, in
FIG. 2, in order to avoid complicating the drawing, the description
of the hatching showing the cross section is omitted.
[0257] As shown in FIG. 2, a light-emitting element 100 includes a
lower substrate 1, an EL light source unit 200 arranged on the
lower substrate 1, a light conversion layer (light-emitting layer)
9 located on the EL light source unit 200 and containing the
light-emitting particles 90, and an upper substrate 11 arranged on
the light conversion layer 9 via an overcoat layer 10. Further, the
EL light source unit 200 includes an anode 2, a cathode 8, and an
EL layer 12 arranged between the anode 2 and the cathode 8.
[0258] The EL layer 12 shown in FIG. 2 includes a hole injection
layer 3, a hole transport layer 4, a light-emitting layer 5, an
electron transport layer 6, and an electron injection layer 7,
which are sequentially laminated from the anode 2 side.
[0259] Such a light-emitting element 100 is a photoluminescence
element in which the light emitted from the EL light source unit
200 (EL layer 12) is incident on the light conversion layer 9, the
light-emitting particles 90 absorb the light, and light having a
color corresponding to the light emitted color is emitted.
[0260] Below, each layer will be described in sequence.
[0261] <<Lower Substrate 1 and Upper Substrate 11>>
[0262] The lower substrate 1 and the upper substrate 11 each have a
function of supporting and/or protecting each layer constituting
the light-emitting element 100.
[0263] When the light-emitting element 100 is a top emission type,
the upper substrate 11 is composed of a transparent substrate. On
the other hand, when the light-emitting element 100 is a bottom
emission type, the lower substrate 1 is composed of a transparent
substrate.
[0264] Here, the transparent substrate means a substrate capable of
transmitting light having the wavelength in the visible light
region, and the transparent includes colorless transparent, colored
transparent, and translucent.
[0265] As the transparent substrate, for example, a glass
substrate, a quartz substrate, a plastic substrate (resin
substrate) composed of polyethylene terephthalate (PET),
polyethylene naphthalate (PEN), polyether sulfone (PES), polyimide
(PI), polycarbonate (PC), and the like, a metal substrate composed
of iron, stainless steel, aluminum, copper, and the like, a silicon
substrate, a gallium arsenic substrate, or the like can be
used.
[0266] Further, when giving flexibility to the light-emitting
element 100, for the lower substrate 1 and the upper substrate 11,
a plastic substrate (a substrate composed of a polymer material as
a main material) and a metal substrate having a relatively small
thickness are selected, respectively.
[0267] The thickness of each of the lower substrate 1 and the upper
substrate 11 is not particularly limited, but is preferably in the
range of 100 to 1,000 .mu.m, and more preferably in the range of
300 to 800 .mu.m.
[0268] Note that either or both of the lower substrate 1 and the
upper substrate 11 can be omitted depending on the usage pattern of
the light-emitting element 100.
[0269] As shown in FIG. 3, on the lower substrate 1, a signal line
drive circuit C1 and a scanning line drive circuit C2 for
controlling the supply of current to the anode 2 constituting the
pixel electrode PE represented by R, G, and B, a control circuit C3
for controlling the operation of these circuits, a plurality of
signal lines 706 connected to the signal line drive circuit C1, and
a plurality of scanning lines 707 connected to the scanning line
drive circuit C2 are provided.
[0270] Further, as shown in FIG. 4, a condenser 701, a drive
transistor 702, and a switching transistor 708 are provided in the
vicinity of the intersection of each signal line 706 and each
scanning line 707.
[0271] In the condenser 701, one electrode is connected to the gate
electrode of the drive transistor 702, and the other electrode is
connected to the source electrode of the drive transistor 702.
[0272] In the drive transistor 702, the gate electrode is connected
to one electrode of the condenser 701, the source electrode is
connected to the other electrode of the condenser 701 and the power
supply line 703 that supplies the drive current, and the drain
electrode is connected to the anode 4 of the EL light source unit
200.
[0273] In the switching transistor 708, the gate electrode is
connected to the scanning line 707, the source electrode is
connected to the signal line 706, and the drain electrode is
connected to the gate electrode of the drive transistor 702.
[0274] Further, in the present embodiment, a common electrode 705
constitutes the cathode 8 of the EL light source unit 200.
[0275] Note that the drive transistor 702 and the switching
transistor 708 can be composed of, for example, a thin film
transistor.
[0276] The scanning line drive circuit C2 supplies or cuts off the
scanning voltage according to the scanning signal to the gate
electrode of the switching transistor 708 via the scanning line
707, and turns on or off the switching transistor 708. As a result,
the scanning line drive circuit C2 adjusts the timing at which the
signal line drive circuit C1 writes the signal voltage.
[0277] On the other hand, the signal line drive circuit C1 supplies
or cuts off the signal voltage according to the video signal to the
gate electrode of the drive transistor 702 via the signal line 706
and the switching transistor 708, and adjusts the amount of the
signal current supplied to the EL light source unit 200.
[0278] Therefore, the scanning voltage is supplied from the
scanning line drive circuit C2 to the gate electrode of the
switching transistor 708, and when the switching transistor 708 is
turned on, the signal voltage is supplied from the signal line
drive circuit C1 to the gate electrode of the switching transistor
708.
[0279] At this time, the drain current corresponding to this signal
voltage is supplied to the EL light source unit 200 as a signal
current from the power supply line 703. As a result, the EL light
source unit 200 emits light in response to the supplied signal
current.
[0280] <<EL Light Source Unit 200>>
[0281] [Anode 2]
[0282] The anode 2 has a function of supplying holes from an
external power source toward the light-emitting layer 5.
[0283] The constituent material of the anode 2 (anode material) is
not particularly limited, but includes, for example, a metal such
as gold (Au), a metal halide such as copper iodide (CuI), metal
oxides such as indium tin oxide (ITO), tin oxide (SnO.sub.2), and
zinc oxide (ZnO). These may be used alone or in combination of two
or more.
[0284] The thickness of the anode 2 is not particularly limited,
but is preferably in the range of 10 to 1,000 nm, and more
preferably in the range of 10 to 200 nm.
[0285] The anode 2 can be formed by, for example, a dry film
forming method such as a vacuum vapor deposition method or a
sputtering method. At this time, the anode 2 having a predetermined
pattern may be formed by a photolithography method or a method
using a mask.
[0286] [Cathode 8]
[0287] The cathode 8 has a function of supplying electrons from an
external power source toward the light-emitting layer 5.
[0288] The constituent material of the cathode 8 (cathode material)
is not particularly limited, but includes, for example, lithium,
sodium, magnesium, aluminum, silver, sodium-potassium alloy,
magnesium/aluminum mixture, magnesium/silver mixture,
magnesium/indium mixture, aluminum/aluminum oxide (Al.sub.2O.sub.3)
mixture, rare earth metals, and the like. These may be used alone
or in a combination of two or more.
[0289] The thickness of the cathode 8 is not particularly limited,
but is preferably in the range of 0.1 to 1,000 nm, and more
preferably in the range of 1 to 200 nm.
[0290] The cathode 3 can be formed by, for example, a dry film
forming method such as a vapor deposition method or a sputtering
method.
[0291] [Hole Injection Layer 3]
[0292] The hole injection layer 3 has a function of receiving the
holes supplied from the anode 2 and injecting them into the hole
transport layer 4. The hole injection layer 3 only needs to be
provided as needed and may be omitted.
[0293] The constituent material of the hole injection layer 3 (hole
injection material) is not particularly limited, but includes, for
example, phthalocyanine compounds such as copper phthalocyanine;
triphenylamine derivatives such as 4,4',4''-tris[phenyl
(m-tolyl)amino]triphenylamine; cyano compounds such as
1,4,5,8,9,12-hexazatriphenylene hexacarbonitrile,
2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane; metal oxides
such as vanadium oxide, molybdenum oxide; amorphous carbon;
polymers such as polyaniline (emeraldine), poly
(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)
(PEDOT)-PSS), polypyrrole, and the like.
[0294] Among these, as the hole injection material, a polymer is
preferable, and PEDOT-PSS is more preferable.
[0295] Further, as the hole injection material described above, one
type may be used alone, or two or more types may be used in a
combination.
[0296] The thickness of the hole injection layer 3 is not
particularly limited, but is preferably in the range of 0.1 to 500
mm, more preferably in the range of 1 to 300 nm, and even more
preferably in the range of 2 to 200 nm.
[0297] The hole injection layer 3 may have a single-layer
configuration or a laminated configuration in which two or more
layers are laminated.
[0298] Such a hole injection layer 4 can be formed by a wet film
forming method or a dry film forming method.
[0299] When the hole injection layer 3 is formed by a wet film
forming method, an ink containing the hole injection material
described above is usually applied by various coating methods, and
the obtained coating film is dried. The coating method is not
particularly limited and includes, for example, an inkjet printing
method (droplet ejection method), a spin coating method, a casting
method, an LB method, a letterpress printing method, a gravure
printing method, a screen printing method, and a nozzle printing
method.
[0300] On the other hand, when the hole injection layer 3 is formed
by a dry film forming method, a vacuum vapor deposition method, a
sputtering method or the like can be preferably used.
[0301] [Hole Transport Layer 4]
[0302] The hole transport layer 4 has a function of receiving holes
from the hole injection layer 3 and efficiently transporting them
to the light-emitting layer 6. Further, the hole transport layer 4
may have a function of preventing the transport of electrons. The
hole transport layer 4 only needs to be provided as needed and may
be omitted.
[0303] The constituent material of the hole transport layer 4 (hole
transport material) is not particularly limited and includes, for
example, low molecular weight triphenylamine derivatives such as
TPD
(N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'diamine),
.alpha.-NPD (4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl),
m-MTDATA (4,4',4''-tris(3-methylphenylphenylamino)triphenylamine);
polyvinylcarbazole; conjugated compound polymers such as
poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine](poly-TPA),
polyfluorene (PF), poly
[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine (Poly-TPD),
poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(sec-butylphenyl)dipheny-
lamine)) (TFB), polyphenylene vinylene (PPV); and copolymers
containing these monomer units.
[0304] Among these, the hole transport material is preferably a
triphenylamine derivative or a polymer compound obtained by
polymerizing a triphenylamine derivative having a substituent
introduced therein, and more preferably a polymer compound obtained
by polymerizing a triphenylamine derivative having a substituent
introduced therein.
[0305] Further, as the hole transport material described above, one
type may be used alone, or two or more types may be used in a
combination.
[0306] The thickness of the hole transport layer 4 is not
particularly limited, but is preferably in the range of 1 to 500
nm, more preferably in the range of 5 to 300 nm, and even more
preferably in the range of 10 to 200 nm.
[0307] The hole transport layer 4 may have a single-layer
configuration or a laminated configuration in which two or more
layers are laminated.
[0308] Such a hole transport layer 4 can be formed by a wet film
forming method or a dry film forming method.
[0309] When the hole transport layer 4 is formed by a wet film
forming method, an ink containing the hole transport material
described above is usually applied by various coating methods, and
the obtained coating film is dried. The coating method is not
particularly limited, and includes, for example, an inkjet printing
method (droplet ejection method), a spin coating method, a casting
method, an LB method, a letterpress printing method, a gravure
printing method, a screen printing method, and a nozzle printing
method.
[0310] On the other hand, when the hole transport layer 4 is formed
by a dry film forming method, a vacuum vapor deposition method, a
sputtering method or the like can be preferably used.
[0311] [Electron Injection Layer 7]
[0312] The electron injection layer 7 has a function of receiving
the electrons supplied from the cathode 8 and injecting them into
the electron transport layer 6. The electron injection layer 7 only
needs to be provided as needed and may be omitted.
[0313] The constituent material of the electron injection layer 7
(electron injection material) is not particularly limited, but
includes, for example, alkali metal chalcogenides such as
Li.sub.2O, LiO, Na.sub.2S, Na.sub.2Se, NaO; alkali earth metal
chalcogenides such as CaO, BaO, SrO, BeO, BaS, MgO, CaSe; alkali
metal halides such as CsF, LiF, NaF, KF, LiCl, KCl, NaCl; alkali
metal salts such as 8-hydroxyquinolinolato lithium (Liq); alkaline
earth metal halides such as CaF.sub.2, BaF.sub.2, SrF.sub.2,
MgF.sub.2, BeF.sub.2, and the like.
[0314] Among these, alkali metal chalcogenides, alkaline earth
metal halides, and alkali metal salts are preferable.
[0315] Further, as the above-mentioned electron injection material,
one type may be used alone, or two or more types may be used in a
combination.
[0316] The thickness of the electron injection layer 7 is not
particularly limited, but is preferably in the range of 0.1 to 100
nm, more preferably in the range of 0.2 to 50 nm, and even more
preferably in the range of 0.5 to 10 nm.
[0317] The electron injection layer 7 may have a single-layer
configuration or a laminated configuration in which two or more
layers are laminated.
[0318] Such an electron injection layer 7 can be formed by a wet
film forming method or a dry film forming method.
[0319] When the electron injection layer 7 is formed by a wet film
forming method, an ink containing the above-mentioned electron
injection material is usually applied by various coating methods,
and the obtained coating film is dried. The coating method is not
particularly limited, and includes, for example, an inkjet printing
method (droplet ejection method), a spin coating method, a casting
method, an LB method, a letterpress printing method, a gravure
printing method, a screen printing method, and a nozzle printing
method.
[0320] On the other hand, when the electron injection layer 7 is
formed by a dry film forming method, a vacuum vapor deposition
method, a sputtering method or the like can be applied.
[0321] [Electron Transport Layer 8]
[0322] The electron transport layer 8 has a function of receiving
electrons from the electron injection layer 7 and efficiently
transporting them to the light-emitting layer 5. Further, the
electron transport layer 8 may have a function of preventing the
transport of holes. The electron transport layer 8 only needs to be
provided as needed and may be omitted.
[0323] The constituent material of the electron transport layer 8
(electron transport material) is not particularly limited, and
includes, for example, metal complex with quinoline skeleton or
benzoquinoline skeleton such as tris(8-quinolilato)aluminum (Alq3),
tris(4-methyl-8-quinolinolato)aluminum (Almq3),
bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq2),
bis(2-methyl-8-uinolinolate) (p-phenylphenolato)aluminum (BAlq),
bis(8-quinolinolate)zinc (Znq); metal complexes with benzoxazoline
skeleton such as bis [2-(2'-hydroxyphenyl)benzoxazolate] zinc
(Zn(BOX)2); metal complex with benzothiazoline skeleton such as
bis[2-(2'-hydroxyphenyl)benzothiazolate] zinc (Zn(BTZ)2); tri- or
diazole derivatives such as
2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxaziazole (PBD),
3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole
(TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene
(OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]carbazole
(CO11); imidazole derivatives such as
2,2',2''-(1,3,5-benzenetriyl)tris (1-phenyl-1H-benzoimidazole)
(TPBI),
2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzoimidazole
(mDBTBIm-II); quinoline derivatives; perylene derivatives; pyridine
derivatives such as 4,7-diphenyl-1,10-phenanthroline (BPhen);
pyrimidine derivatives; triazine derivatives; quinoxaline
derivatives; diphenylquinone derivatives; nitro-substituted
fluorene derivatives; metal oxides such as zinc oxide (ZnO),
titanium oxide (TiO.sub.2), and the like.
[0324] Among these, the electron transport material is preferably
an imidazole derivative, a pyridine derivative, a pyrimidine
derivative, a triazine derivative, or a metal oxide (inorganic
oxide).
[0325] Further, the above-mentioned electron transport materials
may be used alone or in a combination of two or more.
[0326] The thickness of the electron transport layer 7 is not
particularly limited, but is preferably in the range of 5 to 500
nm, and more preferably in the range of 5 to 200 nm.
[0327] The electron transport layer 6 may be a single layer or a
stack of two or more layers.
[0328] Such an electron transport layer 7 can be formed by a wet
film forming method or a dry film forming method.
[0329] When the electron transport layer 6 is formed by a wet film
forming method, an ink containing the electron transport material
described above is usually applied by various coating methods, and
the obtained coating film is dried. The coating method is not
particularly limited, and includes, for example, an inkjet printing
method (droplet ejection method), a spin coating method, a casting
method, an LB method, a letterpress printing method, a gravure
printing method, a screen printing method, and a nozzle printing
method.
[0330] On the other hand, when the electron transport layer 6 is
formed by a dry film forming method, a vacuum vapor deposition
method, a sputtering method or the like can be applied.
[0331] [Light-Emitting Layer 5]
[0332] The light-emitting layer 5 has a function of generating
light emission by utilizing the energy generated by the
recombination of holes and electrons injected into the
light-emitting layer 5.
[0333] The light-emitting layer 5 preferably contains a
light-emitting material (guest material or dopant material) and a
host material. In this case, the mass ratio of the host material
and the light-emitting material is not particularly limited, but is
preferably in the range of 10:1 to 300:1.
[0334] As the light-emitting material, a compound capable of
converting singlet excitation energy into light or a compound
capable of converting triplet excitation energy into light can be
used.
[0335] Further, the light-emitting material preferably contains at
least one selected from the group consisting of an organic
low-molecular fluorescent material, an organic polymer fluorescent
material and an organic phosphorescent material.
[0336] Examples of compounds capable of converting singlet
excitation energy into light include organic low-molecular
fluorescent materials or organic polymer fluorescent materials that
emit fluorescence.
[0337] As the organic low-molecular fluorescent material, a
compound having an anthracene structure, a tetracene structure, a
chrysene structure, a phenanthrene structure, a pyrene structure, a
perylene structure, a stilbene structure, an acridone structure, a
coumarin structure, a phenoxazine structure, or a phenothiazine
structure is preferable.
[0338] Specific examples of the organic low-molecular fluorescent
material include, for example,
5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine,
5,6-bis[4'-(10-phenyl-9-anthril)biphenyl-4-yl]-2,2'-bipyridine (,
N,N'-bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine,
4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthril)triphenylamine,
4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthril)triphenylamine,
N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine,
4-(10-phenyl-9-anthril)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine,
4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazole-3-yl)tripheny-
lamine, perylene, 2,5,8,11-tetra(tert-butyl)perylene,
N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diam-
ine,
N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl)-9H-fluoren-9-yl)phenyl-
]-pyrene-1,6-diamine,
N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine,
N,N'-bis(dibenzothiophen-2-yl)-N,N'-diphenylpyrene-1,6-diamine,
N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triph-
enyl-1,4-phenylenediamine],
N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine,
N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediam-
ine, N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]
chrysene-2,7,10,15-tetraamine, coumarin 30,
N-(9,10-diphenyl-2-anthril)-N,9-diphenyl-9H-carbazole-3-amine,
N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine,
N,N,9-triphenylanthracene-9-amine, coumarin 6, coumarin 545T,
N,N'-diphenylquinacridone, rubrene,
5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene,
2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)pro-
pandinitrile,
2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidine-9-yl)ethe-
nyl]-4H-pyran-4-ylidene}propandinitrile,
N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine,
7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphth[1,2-a]fluoranth-
en-3,10-diamine,
2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i-
j]quinolidine-9-yl)ethenyl]-4H-pyran-4-ylidene}propandinitrile,
2-(2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[-
ij]quinolidine-9-yl)ethenyl]-4H-pyran-4-ylidene)propandinitrile,
2-(2,6-bis(2-[4-(dimethylamino)phenyl]ethenyl)-4H-pyran-4-ylidene)propand-
initrile,
2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1-
H,5H-benzo[ij]quinolidine-9-yl)ethenyl]-4H-pyran-4-ylidene}propandinitrile-
,
5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene,
and the like.
[0339] Specific examples of the organic polymer fluorescent
material include, for example, homopolymers composed of units based
on fluorene derivatives, copolymers composed of units based on
fluorene derivatives and units based on tetraphenylphenylenediamine
derivatives, homopolymers composed of units based on terphenyl
derivatives, homopolymers composed of units based on
diphenylbenzofluorene derivatives, and the like.
[0340] As a compound capable of converting triplet excitation
energy into light, an organic phosphorescent material that emits
phosphorescence is preferable.
[0341] Specific examples of the organic phosphorescent material
include, for example, a metal complex containing at least one metal
atom selected from the group consisting of iridium, rhodium,
platinum, ruthenium, osmium, scandium, yttrium, gadolinium,
palladium, silver, gold, and aluminum.
[0342] Among them, the organic phosphorescent material is
preferably a metal complex containing at least one metal atom
selected from the group consisting of iridium, rhodium, platinum,
ruthenium, osmium, scandium, yttrium, gadrinium, and palladium,
more preferably a metal complex containing at least one metal atom
selected from the group consisting of iridium, rhodium, platinum,
and ruthenium, and even more preferably an iridium complex or a
platinum complex.
[0343] As the host material, it is preferable to use at least one
compound having an energy gap larger than the energy gap of the
light-emitting material. Further, when the light-emitting material
is a phosphorescent material, it is preferable to select a compound
having a triplet excitation energy larger than the triplet
excitation energy (energy difference between the base state and the
triplet excited state) of the light-emitting material as the host
material.
[0344] Examples of the host material include tris
(8-quinolinolato)aluminum (III), tris
(4-methyl-8-quinolinolato)aluminum (III), bis(10-hydroxybenzo[h]
quinolinato)berylium (II), bis(2-methyl-8-quinolinolato)
(4-phenylphenolato) aluminum (III), bis(8-quinolinolato)zinc (II),
bis[2-(2-benzoxazolyl)phenolato] zinc (II),
bis[2-(2-benzothiazolyl)phenolato] zinc (II),
2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole,
1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene,
3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole,
2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzoimidazole),
bathophenanthroline, bathocuproine,
9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole,
9,10-diphenylanthracene,
N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine,
4-(10-phenyl-9-anthryl)triphenylamine,
N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazole-3-a-
mine, 6,12-dimethoxy-5,11-diphenylglycene,
9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole,
3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole,
9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole,
7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole,
6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo [b]naphtho[1,2-d]furan,
9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl)anthracene,
9,10-bis(3,5-diphenylphenyl)anthracene,
9,10-di(2-naphthyl)anthracene,
2-tert-butyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl,
9,9'-(stilbene-3,3'-diyl)diphenanthrene,
9,9'-(stilbene-4,4'-diyl)diphenanthrene,
1,3,5-tri(1-pyrenyl)benzene, 5,12-diphenyltetracene or 5,12-bis
(biphenyl-2-yl)tetracene, and the like. These host materials may be
used alone or in a combination of two or more.
[0345] The thickness of the light-emitting layer 5 is not
particularly limited, but is preferably in the range of 1 to 100
nm, and more preferably in the range of 1 to 50 nm.
[0346] Such a light-emitting layer 5 can be formed by a wet film
forming method or a dry film forming method.
[0347] When the light-emitting layer 5 is formed by a wet film
forming method, an ink containing the above-mentioned
light-emitting material and host material is usually applied by
various coating methods, and the obtained coating film is dried.
The coating method is not particularly limited and includes an
inkjet printing method (droplet ejection method), a spin coating
method, a casting method, an LB method, a letterpress printing
method, a gravure printing method, a screen printing method, and a
nozzle printing method.
[0348] On the other hand, when the light-emitting layer 5 is formed
by a dry film forming method, a vacuum vapor deposition method, a
sputtering method or the like can be applied.
[0349] Note that the EL light source unit 200 may further have, for
example, a bank (partition wall) for partitioning the hole
injection layer 3, the hole transport layer 4, and the
light-emitting layer 5.
[0350] The height of the bank is not particularly limited, but is
preferably in the range of 0.1 to 5 .mu.m, more preferably in the
range of 0.2 to 4 .mu.m, and even more preferably in the range of
0.2 to 3 .mu.m.
[0351] The width of the bank opening is preferably in the range of
10 to 200 .mu.m, more preferably in the range of 30 to 200 .mu.m,
and even more preferably in the range of 50 to 100 .mu.m.
[0352] The length of the bank opening is preferably in the range of
10 to 400 .mu.m, more preferably in the range of 20 to 200 .mu.m,
and even more preferably in the range of 50 to 200 .mu.m.
[0353] Further, the inclination angle of the bank is preferably in
the range of 10 to 100.degree., more preferably in the range of 10
to 90.degree., and even more preferably in the range of 10 to
80.degree..
[0354] <<Light Conversion Layer 9>>
[0355] As shown in FIG. 2, the light conversion layer 9 comprises a
red (R) light conversion pixel unit (NC-Red) including red
light-emitting particles 90, a green (G) light conversion pixel
unit (NC-Green) including nanocrystals for containing green
light-emitting particles 90, and a blue (B) light conversion pixel
unit (NC-Blue) including blue light-emitting particles 90.
[0356] In the light conversion layer 9 having such a configuration,
when the light emitted from the corresponding EL layer 12 is
incident on the light conversion pixel unit (NC-Red, NC-Green,
NC-Blue), the light-emitting nanocrystal 90 convert the light into
light having an emission spectrum in any of red (R), green (G), and
blue (B). That is, the light conversion layer 9 can be said to be a
light-emitting layer.
[0357] Further, a black matrix BM is arranged as a light-shielding
unit between the red light conversion pixel unit (NC-Red), the
green light conversion pixel unit (NC-Green), and the blue light
conversion pixel unit (NC-Blue).
[0358] The red light conversion pixel unit (NC-Red), the green
light conversion pixel unit (NC-Green), and the blue light
conversion pixel unit (NC-Blue) may contain color materials
corresponding to the respective colors.
[0359] The thickness of the light conversion layer 9 is not
particularly limited, but is preferably in the range of 1 to 30
.mu.m, and more preferably in the range of 3 to 20 .mu.m.
[0360] Such a light conversion layer 9 can be formed by a wet film
forming method, and can be formed by supplying the ink composition
of the present invention by various coating methods, drying the
obtained coating film, and then curing by irradiation with active
energy rays (for example, ultraviolet rays), as necessary.
[0361] The coating method is not particularly limited, but for
example, an inkjet printing method (piezo type or thermal type
droplet ejection method), a spin coating method, a casting method,
an LB method, a letterpress printing method, a gravure printing
method, a screen printing method, a nozzle printing method, and the
like. Here, the nozzle printing method is a method of applying the
ink composition from the nozzle holes as a liquid column in a
striped shape.
[0362] Among them, the inkjet printing method (particularly, the
piezo type droplet ejection method) is preferable as the coating
method. As a result, the heat load when ejecting the ink
composition can be reduced, and problems are unlikely to occur in
the light-emitting particles 90 (nanocrystals 91) per se.
[0363] The conditions of the inkjet printing method are preferably
set as follows.
[0364] The ejection amount of the ink composition is not
particularly limited, but is preferably 1 to 50 pL/time, more
preferably 1 to 30 pL/time, and even more preferably 1 to 20
pL/time.
[0365] Further, the opening diameter of the nozzle hole is
preferably in the range of 5 to 50 .mu.m, and more preferably in
the range of 10 to 30 .mu.m. As a result, it is possible to improve
the ejection accuracy of the ink composition while preventing
clogging of the nozzle holes.
[0366] The temperature at which the coating film is formed is not
particularly limited, but is preferably in the range of 10 to
50.degree. C., more preferably in the range of 15 to 40.degree. C.,
and even more preferably in the range of 15 to 30.degree. C. By
ejecting the droplets at such a temperature, crystallization of
various components contained in the ink composition can be
suppressed.
[0367] Further, the relative humidity at the time of forming the
coating film is also not particularly limited, but is preferably in
the range of 0.01 ppm to 80%, more preferably in the range of 0.05
ppm to 60%, even more preferably in the range of 0.1 ppm to 15%,
particularly preferably in the range of 1 ppm to 1%, and most
preferably in the range of 5 to 100 ppm. When the relative humidity
is the above lower limit value or higher, it becomes easy to
control the conditions when forming the coating film. On the other
hand, when the relative humidity is not the above upper limit value
or higher, the amount of water adsorbed on the coating film which
may adversely affect the obtained light conversion layer 9 can be
reduced.
[0368] The obtained coating film may be dried by sitting at room
temperature (25.degree. C.) or by heating.
[0369] When the drying is performed by heating, the drying
temperature is not particularly limited, but is preferably in the
range of 40 to 150.degree. C., and more preferably in the range of
40 to 120.degree. C.
[0370] Further, the drying is preferably performed under reduced
pressure, and more preferably performed under reduced pressure of
0.001 to 100 Pa.
[0371] Further, the drying time is preferably 1 to 90 minutes, and
more preferably 1 to 30 minutes.
[0372] By drying the coating film under such drying conditions, not
only the dispersion medium but also the dispersant and the like can
be reliably removed from the coating film, and the external quantum
efficiency of the obtained light conversion layer 9 can be further
improved.
[0373] When the ink composition is cured by irradiation with active
energy rays (for example, ultraviolet rays), for example, a mercury
lamp, a metal halide lamp, a xenon lamp, an LED or the like is used
as an irradiation source (light source).
[0374] The wavelength of the light to be applied is preferably 200
nm or more, and more preferably 440 nm or less.
[0375] Further, the light irradiation amount (exposure amount) is
preferably 10 mJ/cm.sup.2 or more, and more preferably 4000
mJ/cm.sup.2 or less.
[0376] <<Overcoat Layer 10>>
[0377] The overcoat layer 10 has a function of protecting the light
conversion layer 9 and adhering the upper substrate 11 to the light
conversion layer 9.
[0378] Since the light-emitting element 100 of the embodiment is a
top emission type, it is preferable that the overcoat layer 10 has
transparency (light transmission).
[0379] As the constituent material of the overcoat layer 10, for
example, an acrylic adhesive, an epoxy adhesive, or the like is
preferably used.
[0380] The thickness of the overcoat layer 10 is not particularly
limited, but is preferably in the range of 1 to 100 nm, and more
preferably in the range of 1 to 50 nm.
[0381] The light-emitting element 100 can be configured as a bottom
emission type instead of the top emission type.
[0382] Further, the light-emitting element 100 can use another
light source instead of the EL light source unit 200.
[0383] Further, the light-emitting element 100 can be configured as
an electroluminescence element instead of the photoluminescence
element. In this case, in the element configuration shown in FIG.
2, the light conversion layer 9 may be omitted and the
light-emitting layer 5 may be composed of the light conversion
layer 9.
[0384] Although the method for producing light-emitting particles,
the light-emitting particles, the light-emitting particle
dispersion, the ink composition and the light-emitting element of
the present invention have been described above, the present
invention is not limited to the configuration of the
above-described embodiment.
[0385] For example, the light-emitting particles, the
light-emitting particle dispersion, the ink composition, and the
light-emitting element of the present invention may each have any
other configuration additionally or any configuration that exerts
the same function may be replaced with, in the configuration of the
above-described embodiment.
[0386] Further, the method for producing light-emitting particles
of the present invention may have any other desired step or any
step that exerts the same effect may be replaced with, in the
configuration of the above-described embodiment.
EXAMPLES
[0387] Hereinafter, the present invention will be specifically
described with reference to examples, but the present invention is
not limited thereto.
[0388] 1. Preparation of Parent Particles
[0389] (Parent Particles 1)
[0390] First, 0.81 g of cesium carbonate, 40 mL of 1-octadecene,
and 2.5 mL of oleic acid were mixed to obtain a mixed solution.
Next, the mixed solution was dried under reduced pressure at
120.degree. C. for 10 minutes, and then heated at 150.degree. C.
under an argon atmosphere. As a result, a cesium-oleic acid
solution was obtained.
[0391] On the other hand, 138.0 mg of lead (II) bromide and 10 mL
of 1-octadecene were mixed to obtain a mixed solution. Next, the
mixed solution was dried under reduced pressure at 120.degree. C.
for 10 minutes, and then 1 mL of 3-aminopropyltriethoxysilane was
added to the mixed solution under an argon atmosphere.
[0392] Then, 1.3 mL of the cesium-oleic acid solution was added to
the mixed solution at 140.degree. C., and reacted by heating and
stirring for 5 seconds, and then cooled in an ice bath.
[0393] Next, the reaction solution was stirred in the air
(23.degree. C., humidity 45%) for 60 minutes, and then 20 mL of
ethanol was added.
[0394] The obtained suspension was centrifuged (3,000 rpm, 5
minutes) and the solid matter was recovered.
[0395] This recovered solid matter was added to 16 mL of hexane to
obtain a hexane dispersion of parent particles 1 (0.01 mol/L).
[0396] Note that the nanocrystals of the parent particle 1 were
perovskite-type lead cesium tribromide crystals, and the average
particle size was 10 nm. Further, the surface layer was a layer
composed of 3-aminopropyltriethoxysilane and the thickness thereof
was 1 nm.
[0397] (Parent Particle 2)
[0398] First, 15.0 mg of lead (II) bromide and 4.5 mg of
methylamine hydrobromide was added to 1 mL of N,
N-dimethylformamide solution to obtain a solution containing a raw
material compound for semiconductor nanocrystals.
[0399] On the other hand, 0.18 mL of 3-aminopropyltriethoxysilane,
0.2 mL of oleic acid, and 0.2 mL of toluene were mixed to obtain an
ethoxysilane solution. Then, 29 .mu.L of the above-mentioned
ethoxysilane solution was added to the above-mentioned solution
containing the raw material compound of the semiconductor
nanocrystals in the air at room temperature to obtain a
mixture.
[0400] Immediately after that, the obtained mixture was added to 20
mL of toluene, stirred at room temperature for 5 seconds, and then
centrifuged (12,100 rpm, 5 minutes), and the solid matter was
recovered.
[0401] This recovered solid matter was added to 4 mL of toluene to
obtain a toluene dispersion (0.01 mol/L) of the parent particles
2.
[0402] Note that the nanocrystals of the parent particle 1 were
perovskite-type lead ammonium tribromide crystals and the average
particle size was 11 nm. Further, the surface layer was a layer
composed of 3-aminopropyltriethoxysilane and the thickness thereof
was 1 nm.
[0403] 2. Preparation of Light-Emitting Particles
Example 1
[0404] First, 190 parts by mass of heptane was supplied to a
four-necked flask equipped with a thermometer, a stirrer, a reflux
condenser, and a nitrogen gas introduction tube, and the
temperature was raised to 85.degree. C.
[0405] Next, after reaching the same temperature, a mixture of 66.5
parts by mass of lauryl methacrylate, 3.5 parts by mass of
dimethylaminoethyl methacrylate, and 0.5 parts by mass of
dimethyl-2,2-azobis(2-methylpropionate) dissolved in 20 parts by
mass of heptane was added dropwise to the heptane in the
four-necked flask over 3.5 hours, and even after the addition was
completed, the mixture was kept at the same temperature for 10
hours to continue the reaction.
[0406] After lowering the temperature of the reaction solution to
50.degree. C., a solution of 0.01 part by mass of
t-butylpyrocatechol dissolved in 1.0 part by mass of heptane was
added, and 1.0 part by mass of glycidyl methacrylate was further
added. After that, the temperature was raised to 85.degree. C., and
the reaction was continued at the same temperature for 5 hours. As
a result, a solution containing the polymer (P) was obtained.
[0407] Note that the amount of non-volatile content (NV) contained
in the solution was 25.1% by mass, and the weight average molecular
weight (Mw) of the polymer (P) was 10,000.
[0408] Next, 26 parts by mass of heptane, 3 parts by mass of parent
particles 1, and 3.6 parts by mass of polymer (P) were supplied to
a four-necked flask equipped with a thermometer, a stirrer, a
reflux condenser, and a nitrogen gas introduction tube.
[0409] Further, 0.2 parts by mass of ethylene glycol
dimethacrylate, 0.4 parts by mass of methyl methacrylate, and 0.12
parts by mass of dimethyl-2,2-azobis(2-methylpropionate) were
supplied to the above-mentioned four-necked flask.
[0410] After that, the mixed solution in the four-necked flask was
stirred at room temperature for 30 minutes, then heated to
80.degree. C., and the reaction was continued at the same
temperature for 15 hours. After completion of the reaction, the
polymer that was not adsorbed on the parent particles 1 was
separated by centrifugation, and then the precipitated
light-emitting particles were dispersed in heptane to obtain a
solution of the light-emitting particles 1 in heptane. When
observed with a transmission electron microscope, a polymer layer
having a thickness of about 10 nm was formed on the surfaces of the
parent particles.
Example 2
[0411] A solution of light-emitting particles 2 in heptane was
obtained in the same manner as in Example 1 except that the parent
particles 2 were used instead of the parent particles 1. When
observed with a transmission electron microscope, a polymer layer
having a thickness of about 10 nm was formed on the surfaces of the
parent particles.
Comparative Example 1
[0412] First, 0.814 parts by mass of cesium carbonate, 40 parts by
mass of octadecene, and 2.5 parts by mass of oleic acid were
supplied to a four-necked flask equipped with a thermometer, a
stirrer, a septum, and a nitrogen gas introduction tube, and the
mixture was heated and stirred at 150.degree. C. under a nitrogen
atmosphere until a uniform solution was obtained. After all were
dissolved, it was cooled to 100.degree. C. to obtain a cesium
oleate solution.
[0413] Next, 0.069 parts by mass of lead (II) bromide and 5 parts
by mass of octadecene were supplied to a four-necked flask equipped
with a thermometer, a stirrer, a septum, and a nitrogen gas
introduction tube, and the mixture was heated and stirred at
120.degree. C. for 1 hour under a nitrogen atmosphere. Further, 0.5
parts by mass of oleylamine and 0.5 parts by mass of oleic acid
were supplied, and the mixture was heated and stirred under a
nitrogen atmosphere at 160.degree. C. until a uniform solution was
obtained.
[0414] Next, 0.4 parts by weight of the cesium oleate solution was
supplied, and the mixture was stirred at 160.degree. C. for 5
seconds, and then the reaction vessel was ice-cooled. The obtained
reaction solution was separated by centrifugation and the
supernatant was removed to obtain 0.45 parts by mass of a
perovskite-type cesium lead tribromide crystals in which oleic acid
and oleylamine were coordinated.
[0415] 0.2 parts by mass of the obtained perovskite-type cesium
lead tribromide crystals coordinated with oleic acid and oleylamine
was added to 2 parts by mass of heptane and dispersed to obtain a
heptane solution.
Comparative Example 2
[0416] First, 1.47 parts by mass of lead (II) bromide, 0.45 parts
by mass of methylamine hydrobromide, 1 part by mass of oleylamine,
1 part by mass of oleic acid, and 100 parts by mass of
N,N-dimethylformamide were supplied and dissolved in a four-necked
flask equipped with a thermometer, a stirrer, a septum, and a
nitrogen gas introduction tube.
[0417] Next, the obtained solution was added to 2000 parts by mass
of toluene with vigorous stirring. The obtained reaction solution
was separated by centrifugation and the supernatant was removed to
obtain 1.2 parts by mass of a perovskite-type methylammonium lead
bromide crystals coordinated with oleic acid and oleylamine.
[0418] 0.2 parts by mass of the obtained perovskite-type
methylammonium lead bromide crystals coordinated with oleic acid
and oleylamine was added to 2 parts by mass of heptane and
dispersed to obtain a heptane solution.
[0419] 3. Evaluation of Light-Emitting Particle Dispersion
[0420] 3-1. Quantum Yield Retention Rate
[0421] The quantum yield of the heptane solution obtained in each
Example and each Comparative Example was measured with an absolute
PL quantum yield measuring device ("Quantaurus-QY" manufactured by
Hamamatsu Photonics Co., Ltd.). The quantum yield retention rate of
each heptane solution (value obtained by dividing the quantum yield
after standing in the air for 10 days after preparation by the
quantum yield immediately after preparation) was calculated.
[0422] Note that the higher the quantum yield retention rate, the
higher the stability of the light-emitting particles to oxygen gas
and water vapor.
[0423] 3-2. Dispersion Stability
[0424] The heptane solutions obtained in each Example and each
Comparative Example were left in the air for 10 days, then the
presence or absence of a precipitate was determined and evaluated
according to the following criteria.
[0425] A: No precipitate has formed.
[0426] B: A very small amount of precipitate is formed.
[0427] C: A slightly more precipitate is generated.
[0428] These results are summarized in Table 1 below.
TABLE-US-00001 TABLE 1 Quantum Yield Retention Rate (%) Dispersion
Stability Example 1 95 B Example 2 86 A Comparative 76 C Example 1
Comparative 72 C Example 2
[0429] From the results in Table 1, it can be seen that the
light-emitting particles produced by the production method of the
present invention have high stability to oxygen gas and water
vapor, and high dispersion stability to heptane.
[0430] 4. Ink Composition and Light Conversion Layer
[0431] <Preparation of Light-Emitting
Particles/Photopolymerizable Compound Dispersion>
Preparation Example 1
[0432] Heptane is removed from the heptane solution obtained in
Example 1 by a rotary evaporator, and then lauryl acrylate
(manufactured by Kyoeisha Chemical Co., Ltd.), a photopolymerizable
compound, is mixed and stirred by the rotary evaporator to obtain
light-emitting particles/photopolymerizable compound dispersion 1
(content of light-emitting particles 1: 50% by mass).
Preparation Example 2
[0433] Light-emitting particles/photopolymerizable compound
dispersion 2 (content of light-emitting particles 2: 50% by mass)
was obtained in the same manner as in Preparation Example 1 except
that the heptane solution obtained in Example 2 was used instead of
the heptane solution obtained in Example 1.
[0434] <Preparation of Light-Scattering Particle
Dispersion>
[0435] First, 55 parts by mass of titanium oxide particles
(manufactured by Teika Co., Ltd., "JR-806"), 2 parts by mass of a
high-molecular dispersant (manufactured by BYK Chemie, "Ajisper
PB-821"), and 45 parts by mass of 1,6-hexanediol diacrylate
(manufactured by Kyoeisha Chemical Co., Ltd.), which is a
photopolymerizable compound, and 0.03 parts by mass of
4-methoxyphenol (manufactured by Seiko Chemical Co., Ltd.,
"METHOQUINONE"), which is a polymerization inhibitor were blended.
Note that the average particle size (volume average diameter) of
the titanium oxide particles is 300 nm.
[0436] Next, after adding zirconia beads (diameter: 0.3 mm) to the
obtained formulation, the formulation was dispersed by shaking for
2 hours using a paint conditioner. As a result, a light scattering
particle dispersion 1 was obtained.
Example 3
[0437] First, 27.5 parts by mass of 1,6-hexanediol diacrylate'', a
photopolymerizable compound, was mixed with 3 parts by mass of a
photopolymerization initiator (manufactured by IGM Resin, "Omnirad
TPO") and 0.5 parts by mass of an antioxidant (manufactured by
Johoku Chemical Co., Ltd., "JPE-10") and stirred at room
temperature to uniformly dissolve.
[0438] 65 parts by mass of light-emitting
particles/photopolymerizable compound dispersion 1 and 4 parts by
mass of light scattering particle dispersion 1 were further mixed
with the obtained solution, and the mixture was stirred at room
temperature to uniformly disperse.
[0439] Next, the obtained dispersion liquid was filtered through a
filter having a pore size of 5 .mu.m to obtain an ink composition
1.
[0440] Next, the obtained ink composition 1 was applied onto a
glass substrate ("EagleXG" manufactured by Corning Inc.) with a
spin coater so that the film thickness after drying was 10
.mu.m.
[0441] The obtained film was irradiated with ultraviolet light
having the LED lamp wavelength of 365 nm under a nitrogen
atmosphere at an exposure amount of 2000 mJ/cm.sup.2. As a result,
the ink composition 1 was cured to form a layer (light conversion
layer 1) made of the cured product of the ink composition on the
glass substrate.
Example 4
[0442] Ink composition 2 was obtained in the same manner as in
Example 3 except that the heptane solutions obtained in Example 2
was used instead of the heptane solution obtained in Example 1. A
light conversion layer 2 was obtained in the same manner as in
Example 3 except that the ink composition 2 was used.
Comparative Example 3
[0443] Ink composition C1 was obtained in the same manner as in
Example 3 except that the heptane solutions obtained in Comparative
Example 1 was used instead of the heptane solution obtained in
Example 1. A light conversion layer c1 was obtained in the same
manner as in Example 3 except that the ink composition C1 was
used.
Comparative Example 4
[0444] An ink composition C2 was obtained in the same manner as in
Example 3 except that the heptane solution obtained in Comparative
Example 2 was used instead of the heptane solution obtained in
Example 1. A light conversion layer c2 was obtained in the same
manner as in Example 3 except that the ink composition C2 was
used.
[0445] 5. Evaluation of Ink Composition and Light Conversion
Layer
[0446] The ink composition and the light conversion layer obtained
above were evaluated for ejection stability, external quantum
efficiency retention rate, and surface smoothness by the following
procedure.
[0447] 5-1. Ejection Stability of Ink Composition
[0448] Using an inkjet printer (manufactured by Fuji Film Dimatix,
"DMP-2831"), the ink composition was continuously ejected for 10
minutes and evaluated according to the following criteria.
[0449] Note that 16 nozzles are formed in the head portion of the
inkjet printer for ejecting ink, and the amount of the ink
composition used per nozzle per ejection was 10 .mu.L.
[0450] A: Continuous ejection is possible (10 or more nozzles out
of 16 nozzles can continuously eject)
[0451] B: Continuous ejection is not possible (out of 16 nozzles,
the number of nozzles that can continuously eject is 9 or less)
[0452] C: Ejection not possible
[0453] 5-2. External Quantum Efficiency Retention Rate of Light
Conversion Layer
[0454] The external quantum efficiency each of immediately after
the formation of the obtained light conversion layer and after
storage under the atmosphere for 10 days was measured as follows,
and the external quantum efficiency retention rate of the light
conversion layer (the value obtained by dividing the external
quantum efficiency 10 days after the formation of the light
conversion layer by the external quantum efficiency immediately
after the formation of the light conversion layer) was
calculated.
[0455] A blue LED (peak emission wavelength 450 nm; manufactured by
CCS Inc.) was used as a surface emission light source, and a light
conversion layer was installed on this light source with the glass
substrate side facing down.
[0456] An integrating sphere was connected to a radiation
spectrophotometer ("MCPD-9800" manufactured by Otsuka Electronics
Co., Ltd.), and the integrating sphere was brought close to the
light conversion layer installed on the blue LED. In this state,
the blue LED was turned on, the quantum numbers of the excitation
light and the emission (fluorescence) of the light conversion layer
were measured, and the external quantum efficiency was
calculated.
[0457] Note that the higher the external quantum efficiency
retention rate, the higher the stability of the light conversion
layer containing light-emitting particles to oxygen gas and water
vapor.
[0458] 5-3. Surface Smoothness of Light Conversion Layer
[0459] The surface of the obtained light conversion layer was
observed with an atomic force microscope (AFM), and the surface
roughness Sa was measured.
[0460] These results are summarized in Table 2 below.
TABLE-US-00002 TABLE 2 External Quantum Light Efficiency surface
Ink Com- conversion Ejection Retention roughness position layer
stability Rate (%) Sa (.mu.m) Example 3 1 1 A 96 0.05 Example 4 2 2
B 92 0.07 Comparative C1 c1 C 50 0.20 Example 3 Comparative C2 c2 C
44 0.29 Example 4
[0461] As shown in Table 1, it was found that the light-emitting
particle dispersions of Examples 1 and 2 coated with the polymer
layer were excellent in the quantum yield retention rate and the
dispersion stability. Further, as shown in Table 2, the ink
compositions prepared from the light-emitting particle dispersions
of Examples 1 and 2 coated with the polymer layer have excellent
inkjet ejection stability, and the formed light conversion layer
was found that the external quantum efficiency retention rate and
surface smoothness were excellent.
REFERENCE SIGNS LIST
[0462] 100: Light-emitting element [0463] 200: EL light source unit
[0464] 1: Lower substrate [0465] 2: Anode [0466] 3: Hole injection
layer [0467] 4: Hole transport layer [0468] 5: Light-emitting layer
[0469] 6: Electron transport layer [0470] 7: Electron injection
layer [0471] 8: Cathode [0472] 9: Light conversion layer [0473] 10:
Overcoat layer [0474] 11: Upper substrate [0475] 12: EL layer
[0476] 90: Light-emitting element [0477] 91: Parent particle [0478]
911: Nanocrystals [0479] 912: Surface layer [0480] 92: Polymer
layer [0481] 701: Condenser [0482] 702: Drive transistor [0483]
705: Common electrode [0484] 706: Signal line [0485] 707: Scanning
line [0486] 708: Switching transistor [0487] C1: Signal line drive
circuit [0488] C2: Scanning line drive circuit [0489] C3: Control
circuit [0490] PE, R, G, B: Pixel electrodes
* * * * *